Description |
PASCOS 2019 aims to review and discuss recent progress in particle physics, string theory and cosmology, bringing together researchers to report and discuss what has been learnt and what might show up in the next few years. Topics will include new physics at LHC, gravitational waves, neutrinos and non-accelerator probes of new physics, string theory and new results in cosmology. This edition of PASCOS will take place at the University of Manchester from 1 to 5 July 2019, and will be the 25th conference in this series. The conference includes invited plenary talks as well as parallel sessions. We particularly welcome and encourage the participation of early career researchers. |
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The Local Organising Committee | Email: pascos2019@manchester.ac.uk Telephone: +44 (0)161 275 4171 |
Convener: | Prof. Pran Nath (Northeastern University) |
Location: | Schuster ( Rutherford Lecture Theatre ) |
Speaker: | Dr. Andrey Pozdnyakov (Aachen U.) |
Material: | Slides |
Convener: | Prof. Ignatios Antoniadis (LPTHE Paris and AEC Bern) |
Location: | Schuster ( Rutherford Lecture Theatre ) |
Speaker: | Dr. Evelyn Jean Thomson (Pennsylvania U.) |
Material: | Slides |
Speaker: | Prof. Masahito Yamazaki (Kavli IPMU, University of Tokyo) |
Material: | Slides |
Speaker: | Prof. Daniel Litim (University of Sussex) |
Material: | Slides |
Conveners: | Dr. Fedor Bezrukov (The University of Manchester) |
Location: | Schuster ( Rutherford Lecture Theatre ) |
I will introduce our recent proposal that the state of the universe does *not* spontaneously violate CPT. Instead, the universe after the big bang is the CPT image of the universe before it, both classically and quantum mechanically. The pre- and post-bang epochs comprise a universe/anti-universe pair, emerging from nothing directly into a hot, radiation-dominated era. CPT symmetry selects the QFT vacuum state on such a spacetime, providing a new interpretation of the cosmological baryon asymmetry, as well as an economical explanation for the cosmological dark matter. Requiring only the standard three-generation model of particle physics (with right-handed neutrinos), a Z_2 symmetry suffices to render one of the right-handed neutrinos stable. We calculate its abundance from first principles: matching the observed dark matter density requires its mass to be 4.8 x 10^{8} GeV. Several other testable predictions follow: (i) the three light neutrinos are Majorana and allow neutrinoless double beta decay; (ii) the lightest neutrino is massless; and (iii) there are no primordial long-wavelength gravitational waves. The proposal also has interesting connections to the strong CP problem and the observed electrodynamic arrow of time. (Based on Phys.Rev.Lett. 121 (2018) 251301, and forthcoming work.)
Speaker: | Latham Boyle (Perimeter Institute) |
Material: | Slides |
Several recent proposals to embed inﬂation into high-energy physics rely on inﬂationary dynamics characterized by a strongly non-geodesic motion. This in turn relaxes the conditions of slow-roll to allow for potentials that are steep in Planck units, a welcome feature in view of the eta problem and the recently much discussed swampland conjectures. In this talk I will present a general framework to study non-Gaussianities in these type of models. This consists in deriving a non-standard single-ﬁeld eﬀective ﬁeld theory with imaginary speed of sound supported by first-principle numerical computations. I will then highlight how non-geodesic trajectories in fields space naturally leads to “hyper non-Gaussianities” and a possible loss of perturbative control. This allow us to derive model-independent constraints which sharpen the range of allowed theoretical constructions.
Speaker: | Dr. Jacopo Fumagalli (IAP Paris) |
Material: | Slides |
Geometry has long been an important tool in physics, finding it's place in everything from Einstein's theory of General Relativity to the structure of Lie groups in Quantum Field Theory. In this talk I will extend the reach of geometry even further by presenting the Eisenhart lift. This formalism allows the classical dynamics of any scalar field theory to be re-expressed as a consequence of the geometry of a curved manifold. I will show how this formalism can provide a new outlook on theories of inflation, and potentially a novel solution to the measure problem. This talk is based on arXiv:1806.02431 and arXiv:1812.07095.
Speaker: | Mr. Kieran Finn (University of Manchester) |
Material: | Slides |
In this talk I will discuss how different inflationary models are sensitive to inhomogeneities in the initial scalar field profile. In particular I will demonstrate that convex potentials always support large inhomogeneities and are more robust than concave ones. We developed a prescription to predict when a concave inflationary potential fails and I will show how it can be used to infer the initial conditions needed for a given model to be safe.
Speaker: | Josu C. Aurrekoetxea (King's College London) |
Material: | Slides |
Bouncing cosmological solutions are found in a simple model of Einstein gravity coupled non-minimally to a self-interacting real scalar field. The characteristics of the solutions are presented and analyzed with an effective potential as a central tool. Bouncing solutions exist for the Higgs-like self interaction which is bounded from below, contrary to previous claims in favor of unbounded potentials. Appearance of higher power terms in the potential, gives rise to bouncing solutions even if the self-interaction potential has a symmetric minimum only. The bouncing solutions exist in a finite domain in parameter space with nonzero measure in the space of initial conditions. In other regions of parameter space, solutions with a Big Bang behavior exist, as well as others.
Speaker: | Prof. Yosef Verbin (Dept. of Natural Sciences, The Open University of Israel) |
Material: | Slides |
Conveners: | Prof. Vincenzo Branchina (University of Catania) |
Location: | Schuster ( Bragg Lecture Theatre ) |
The minimal standard model, viewed as an effective theory with spontaneously broken scale invariance, predicts light, feebly coupled dilaton. Although, the microscopic physics is almost indistinguishable from the standard model, the cosmological evolution is entirely different due to the presence of nearly flat direction in the Higgs-dilaton potential. Most notably, the electroweak phase transition is necessarily driven by the QCD chiral symmetry breaking phase transition, and thus occurs at ~100 MeV. This opens a novel scenario for the electroweak baryogenesis, which I will describe in this talk.
Speaker: | Prof. Archil Kobakhidze (The University of Sydney) |
Material: | Slides |
We discuss how the Standard Model becomes scale invariant at the quantum level above a certain value of the Higgs field value without addition of new degrees of freedom. We see some cosmological consequences of this setup, especially, absolute stability of the electroweak vacuum can be realized even with the current central experimental value of the top quark mass.
Speaker: | Dr. Kengo Shimada (EPFL) |
Material: | Slides |
In scale-invariant theories of gravity the Planck mass, which appears due to spontaneous symmetry breaking, can represent the only energy scale at the classical level. We discuss the possibility for the second scale, associated with the Higgs vacuum expectation value, to be generated by a quantum non-perturbative gravitational effect. The new scale can be orders of magnitude below the Planck scale, leading to the hierarchy between the electroweak and the gravitational forces. The effect is manifested in the existence of an instanton configuration contributing to the vacuum expectation value of the Higgs field. We study such configurations in several classes of theories motivated by phenomenology and identify conditions for the successful implementation of the mechanism.
Speaker: | Dr. Andrey Shkerin (EPFL) |
Material: | Slides |
I discuss asymptotically safe extensions of the Standard Model with new matter fields at the TeV scale. The BSM sector contains singlet scalars and vector-like fermions in representations which permit Yukawa interactions with the Standard Model leptons and a Higgs portal coupling. Phenomenological implications are explored including production and decay mechanisms, charged lepton flavour violation, Drell-Yan processes and lepton anomalous magnetic moments. Moreover, UV safety is discussed up to the Planck regime in dependence of the BSM couplings. Scenarios are highlighted which avoid Landau poles, stabilise the Higgs sector and accommodate for the muon anomalous magnetic moment.
Speaker: | Mr. Tom Steudtner (U Sussex) |
Material: | Slides |
Motivated by an alternative description of the Higgs sector, we present an non-Hermitian but PT-symmetric extension of scalar-QED. This extenion involves an imaginary mixing mass term for scalars, but keeps real energies. Fundamental concepts of field theory must be questioned in this approach, like the derivation of the equations of motion, Noether's theorem, gauge invariance, the definition of path integral, ... and we show how a consistent model is possible.
Speaker: | Dr. Jean Alexandre (King's College London, Department of Physics) |
Material: | Slides |
Conveners: | Dr. Radu Tatar (University of Liverpool) |
Location: | Schuster ( Annex: Bell Burnell Lecture Theatre ) |
Solving non-perturbative, real-time dynamics of quantum field theory is big challenge. In this presentation we shall describe how Cauchy's theorem, and a sojourn into complex field-space, allows for the solution of the real-time path integral. This is achieved by showing that the Schwinger-Keldysh calculation may be split into two pieces, which ultimately guarantees a single saddle point in the Monte Carlo calculations, thus avoiding the multi-modal problem.
Speaker: | Dr. Paul Saffin (University of Nottingham) |
Material: | Slides |
We construct type I string models where supersymmetry is spontaneously broken, which have exponentially small cosmological constant and are tachyon free at 1-loop. These theories have rigid Wilson lines associated with stacked branes. Models with positive effective potentials of runaway type are also presented.
Speaker: | Dr. Hervé Partouche (Ecole Polytechnique-CNRS) |
Material: | Slides |
Flavor symmetry plays a crucial role in the standard model of particle physics but its origin is still unknown. A new method is presented to determine flavor symmetries within compactified string theory. This method is based on the outer automorphisms of the Narain space group of an orbifold. The resulting flavor symmetries are hence closely related to modular symmetries (i.e. T-duality). By applying this method to the T2/Z3 orbifold, one observes that the generic Delta(54) flavor symmetry gets enhanced on certain loci in moduli space. In contrast to Delta(54), which induces a geometrical CP-violation, these higher order flavor groups contain CP-like symmetries. Hence flavor, CP, and modular symmetries are combined. Furthermore, this setup allows for models where CP is spontaneously broken by the VEV of the T-modulus.
Speaker: | Mr. Alexander Baur (Technical University of Munich) |
Material: | Slides |
While most particle physics models from string theory have been constructed in settings with some amount of supersymmetry, there has not been any experimental evidence, that it is actually realized in nature. We show that by starting from non-supersymmetric heterotic strings it is possible to construct models which have particle spectra surprisingly close to that of the Standard Model of particle physics. However, all these models seem to suffer from at least two caveats: The spectrum contains a large number of additional states, which do not have clear physical interpretation. A huge cosmological constant seems to be always generated at the one-loop level in conflict with the observed experimental value and leading to various stability issues.
Speaker: | Dr. Stefan Groot Nibbelink (Rotterdam University of Applied Sciences) |
Material: | Slides |
We offer a geometric interpretation of attractor theories with singular kinetic terms as a union of multiple canonical models. We demonstrate that different domains (separated by poles) can drastically differ in their phenomenology. We illustrate this with the help of a "master model'' that leads to distinct predictions depending on which side of the pole the field evolves before examining the more realistic example of α-attractor models. Such models lead to quintessential inflation within the poles when featuring an exponential potential. However, beyond the poles, we discover a novel behaviour: the scalar field responsible for the early-time acceleration of the Universe reaches the boundary of the field-space manifold, indicating that the theory is incomplete and that a boundary condition must be imposed in order to determine the late-time behaviour of such theories. Turning to multifield models with singular kinetic terms, we see that poles generalise straightforwardly to singular curves, which act as "model walls'' between distinct pole-free inflationary models. As an example, we study a simple two-field α-attractor-inspired model, whose evolution of isocurvature perturbations is sensitive to where the non-canonical field begins its trajectory. We finally discuss initial conditions in attractor theories, where the existence of multiple disconnected canonical models implies that we must make a fundamental choice: in which domain we impose a distribution for the inflaton in order to then determine the likelihood of inflation.
Speaker: | Dr. Sotirios Karamitsos (Lancaster University) |
Material: | Slides |
Conveners: | Prof. Jose W. F. Valle (Valencia U.) |
Location: | Schuster ( Moseley Lecture Theatre ) |
A non-relativistic theory effective field theory (NREFT) offers a bottom-up framework to classify Dark Matter (DM) - nucleon interactions relevant for scattering at direct detection experiments by organising the interactions in powers of the momentum transfer $ \vec{q} $. This approach generates a number of operators including P-odd and T-odd operators, which require that the relativistic theory generating them have CP violating interactions. We consider the leading order P-odd, T-odd operators viz. $ \mathcal{O}_{10} $, $ \mathcal{O}_{11} $ and $ \mathcal{O}_{12} $ and compare the constraints on these operators from leading direct detection searches and neutron EDM (nEDM). To that end, we perform our analysis using simplified models with charged mediators and compute the loop diagrams contributing to nEDM. We find that constraints on DM scattering cross section from nEDM are several orders of magnitude stronger than the limits from direct searches and the neutrino floor for such NREFT operators for the entire sub-GeV and GeV DM mass range. Our results have interesting implications for prospects of detecting such interactions at direct searches and the NREFT formalism.
Speaker: | Mr. Rahul Mehra (University of Bonn) |
Material: | Slides |
The implications of the Dark-LMA solution to the solar neutrino problem for neutrino-less double beta decay will be discussed. It will be shown that while the predictions for the effective mass governing neutrino-less double beta decay remains unchanged for the inverted mass scheme, that for normal ordering becomes higher for the Dark-LMA parameter space and hits into the ``desert region'' between the two. This can set a new goal for sensitivity reach for the next generation neutrino-less double beta decay experiments if no signal is found for the inverted ordering by the future search programmes.
Speaker: | Prof. Srubabati Goswami (Physical Research Laboratory/Imperial College London) |
Material: | Slides |
We discuss lepton number violating processes in the context of long-baseline neutrino oscillations. We summarise and compare neutrino flavour oscillations in quantum mechanics and quantum field theory, both for standard oscillations and those that violate lepton number. When the active neutrinos are Majorana in nature, the required helicity-reversal gives a strong suppression by the neutrino mass over the energy, (mν/Eν)2. Instead, the presence of non-standard lepton number violating interactions incorporating right-handed lepton currents at production or detection alleviate the mass suppression while also factorising the oscillation probability from the total rate. Such interactions arise from dimension-six operators in the low energy effective field theory of the Standard Model. We derive general and simplified expressions for the lepton number violating oscillation probabilities and use limits from MINOS and KamLAND to place bounds on the interaction strength in interplay with the unknown Majorana phases in neutrino mixing. We compare the bounds with those from neutrinoless double beta decay and other microscopic lepton number violating processes and outline the requirements for future short- and long-baseline neutrino oscillation experiments to improve on the existing bounds.
Speaker: | Mr. Patrick Bolton (University College London) |
Material: | Slides |
In the development of atomic clocks, some atomic transition frequencies are measured with remarkable precision. These measured spectra may include effects of a new force mediated by a weakly interacting boson. Such effects might be distilled out from possible violation of a linear relation in isotope shifts between two transitions, as known as King's linearity, with relatively suppressed theoretical uncertainties. We discuss the experimental sensitivity to a new force in the test of the linearity as well as the linearity violation owing to higher order effects within the Standard Model. The sensitivity to new physics is limited by such effects. We have found that for Yb$^+$, the higher order effect is in the reach of future experiments. The sensitivity to a heavy mediator is also discussed. It is analytically clarified that the sensitivity becomes weaker than that in the literature. Our numerical results of the sensitivity are compared with other weak force search experiments. We also discuss some recent developments including the relativistic effect.
Speaker: | Dr. Yasuhiro Yamamoto (National Center for Nuclear Research) |
Material: | Slides |
We explore the possibility that dark matter interactions with Standard Model particles are dominated by interactions with neutrinos. We examine whether it is possible to construct such a scenario in a gauge-invariant manner. We first study the coupling of dark matter to the full lepton doublet and confirm that this generally leads to the dark matter phenomenology being dominated by interactions with charged leptons. We then explore two different implementations of the neutrino portal in which neutrinos mix with a Standard Model singlet fermion that interacts directly with dark matter through either a scalar or vector mediator. In these cases we find that the neutrino interactions can dominate the dark matter phenomenology. Present neutrino detectors can probe dark matter annihilations into neutrinos and already set the strongest constraints on these realisations. Future experiments such as Hyper-Kamiokande, MEMPHYS, DUNE, or DARWIN could allow to probe dark matter annihilation cross section to neutrinos down to the value required to obtain the correct thermal relic abundance.
Speaker: | Dr. Arsenii Titov (IPPP, Durham University) |
Material: | Slides |
Conveners: | Prof. Dmitry Gorbunov (INR RAS) |
Location: | Schuster ( Blackett Lecture Theatre ) |
We present a simple extension of the Standard Model that contains, as the only new physics component, a massive spin-one matter field in the adjoint representation of SU(2)L. In order to be consistent with perturbative unitarity, the vector field must be odd under a Z2 symmetry. Radiative corrections make the neutral component of the triplet (V0) slightly lighter than the charged ones. We show that V0 can be the dark matter particle while satisfying all current bounds if it has a mass between 2.8 and 3.8 TeV. We present the current limit on the model parameter space from highly complementary experimental constraints including dark matter relic density measurement, dark matter direct and indirect detection searches, LHC data on Higgs couplings to photons and LHC data on disappearing track searches. We also show that the two-dimensional parameter space can be fully covered by disappearing track searches at a future 100 TeV hadron collider, which will probe, in particular, the whole mass range relevant for dark matter, thus giving an opportunity to discover or exclude the model. Based on arXiv:1808.10464
Speaker: | Prof. Alexander Belyaev (University of Southampton) |
Material: | Slides |
We explore an extension to the Standard Model which incorporates a vector field in the fundamental representation of SU(2)L as the only nonstandard degree of freedom. We study the model in which a Z2 symmetry is manifest, making the neutral CP-even component of the new vector field a vectorial dark matter candidate. We constraint the parameter space through LEP and LHC data, as well as from current dark matter searches. We find that the model is highly constrained but a small region of the parameter space can provide a viable DM candidate. On the other hand, unitarity demands an UV completion at an scale below 10 TeV. Finally we contrast our predictions on mono-jet, -Z, -Higgs production with the ones obtained in the inert two Higgs doublet model.
Speaker: | Dr. Felipe Rojas Abatte (University of Southampton) |
Material: | Slides |
We revisit the simplest model of Higgs portal fermionic dark matter. The dark matter in this scenario is thermally produced in the early universe due to the interactions with the Higgs boson which is described by a non-renormalisable dimension-5 operator. The dark matter-Higgs scattering amplitude grows as ∝s√, signalling a breakdown of the effective description of the Higgs-dark matter interactions at large enough (compared to the mass scale Λ of the dimention-5 operator) energies. Therefore, in order to reliably compute Higgs-dark matter scattering cross sections, we employ the K-matrix unitarisation procedure. To account for the desired dark matter abundance, the unitarised theory requires appreaciably smaller Λ than the non-unitarised version, especially for dark matter masses around and below the Higgs resonance, mχ≲65 GeV, and mχ≳ few TeV. Consequently, we find that the pure scalar CP-conserving model is fully excluded by current direct dark matter detection
Speaker: | Mr. Shyam Balaji (The University of Sydney) |
Material: | Slides |
Galactic-scale structures can play an important role in pinning down dark matter properties. While weakly interacting massive particles (WIMPs) behave as cold dark matter on galactic scales, it is known that many beyond-WIMP candidates suppress the linear matter power spectrum. Though the suppression has been traditionally parametrized by a single parameter, thermal warm dark matter mass, the actual suppression in the matter power depends on the underlying mechanism and is much more complicated. Thus, in order to prepare for future observational improvement, it is necessary to (1) introduce a parameter set that covers a wide range of beyond-WIMP models, and (2) develop a method to connect such parameters with the underlying model parameters and/or observables in an efficient manner. In this talk we propose using neural network technique for the latter purpose. We demonstrate how the connection is realized in a ready-to-use manner by neural network, taking light feebly interacting massive particles (FIMPs) as an example.
Speaker: | Dr. Ryusuke Jinno (DESY) |
Material: | Slides |
We present limits on several Dark Sector models obtained by BaBar. Primarily designed for the study of CP violation in B mesons, this experiment is also, thanks to the high luminosity delivered and its powerful particle identification, sensitive to many other interesting physics processes. These include production of visible and invisible dark photons, for which. our limits rule out the parameter space favoured by the apparent g-2 anomaly. We also present limits on a Z' coupling preferentially to muons, and on a light Higgs.
Speaker: | Prof. Roger Barlow (University of Huddersfield) |
Material: | Slides |
Conveners: | Prof. Alexander Belyaev (Southampton University) |
Location: | Schuster ( Blackett Lecture Theatre ) |
Presented is a proposed search for ultra light dark matter with the Atomic Interferometric Observatory and Network (AION)- a UK led initiative to design and build a multipurpose atom interferometer with the goal of probing the properties of dark matter and paving the way to detecting gravitational waves in the largely unexplored mid-band frequency range. The plan is to build a set of atom interferometers with progressively larger baselines, taking advantage of the design features used by the world's best atomic clocks in combination with established techniques for building inertial sensors. The key experimental features of the interferometer and the type of dark matter models that can be probed is presented.
Speaker: | Dr. Sarah Malik (Imperial College London) |
Material: | Slides |
Lepton number violation is notoriously difficult to observe with left-handed sneutrinos as sneutrino-antisneutrino oscillation requires the sneutrinos to be nearly degenerate. This situation is alleviated with right-handed sneutrinos. We discuss the possibility of observing lepton number violating sneutrino decays in the NMSSM extended with right-handed neutrinos. If higgsinos are lighter than sneutrinos, the sneutrinos may decay visibly and we may obtain a same-sign dilepton signature from sneutrino pair production.
Speaker: | Dr. Harri Waltari (STFC RAL) |
Material: | Slides |
Presence of nonholomorphic soft SUSY breaking terms is known to be a possibility in the popular setup of the Minimal Supersymmetric Standard Model (MSSM). It has been shown that such a scenario known as NonHolomorphic Supersymmetric Standard Model (NHSSM) could remain `natural' ( i.e., not fine-tuned) even in the presence of a rather heavy higgsino-like LSP. However, it turns out that distinguishing such a scenario from the MSSM is unlikely to be an easy task, in particular at the Large Hadron Collider (LHC). In a first study of such a scenario at colliders (LHC), we explore a possible way that focuses on the sbottom phenomenology. This exploits the usual tanβ-dependence (enhancement) of the bottom Yukawa coupling but reinforced/altered in the presence of non-vanishing nonholomorphic soft trilinear parameter A′b. For a given set of masses of the sbottom(s) and the light electroweakinos (LSP, lighter chargino etc.) which are known from experiments, the difference between the two scenarios could manifest itself via event rate in the 2b-jets + /ET final state, which could be characteristically different from its MSSM expectation. Impact on the phenomenology of the stops at the LHC is also touched upon.
Speaker: | Prof. Utpal Chattopadhyay (Indian Association for the Cultivation of Science) |
Material: | Slides |
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has completed a commissioning run, achieved a peak luminosity of $5.5\times 10^{33}$ cm$^{-2}$s$^{-1}$, and Belle II has recorded a data sample of about 0.5 fb$^{-1}$. Main operation of SuperKEKB has started in March 2019.. Already this early data set with specifically designed triggers offers the possibility to search for a large variety of dark sector particles in the GeV mass range complementary to LHC and dedicated low energy experiments; these searches will benefit from more data in the process of being accumulated. This talk will review the state of the dark sector searches at Belle II with a focus on the discovery potential of the early data, and show the first results
Speaker: | Alberto Martini (University & INFN Roma Tre) |
Material: | Slides |
Conveners: | Dr. Peter Millington (University of Nottingham) |
Location: | Schuster ( Annex: Bell Burnell Lecture Theatre ) |
At low energies, the world around us can be described very accurately using the Standard Model and \Lambda CDM. However, these are at best only ``effective'' descriptions: valid at low energies but destined to break down as experiments in particle physics and cosmology probe increasingly higher energies, ultimately requiring a new (UV complete) theory to take over. In this talk, I will review the constraints which must be placed on our low-energy Effective Field Theories if they are to have any hope of a smooth Wilsonian UV completion at high energies (which is unitary, causal and local). These constraints are known as ``positivity bounds''. Exploiting such connections between the IR and the UV in order to constrain our IR model-building is particularly important for cosmology and gravity, as they are able to rule out large regions of parameter space on purely theoretical grounds (i.e. only certain models could ever make physical sense at high energies), complementing and strengthening our ever-improving experimental tests. For instance, by applying positivity constraints as theoretical priors on a Monte Carlo Markov Chain analysis, we have recently improved the experimental constraints on Horndeski scalar-tensor models by a factor of 100. And this is just using our current CMB, BAO, matter power spectrum and RSD data (Planck/SDSS/BOSS/6dF)---as our future cosmological measurements increase in precision, the role of positivity in determining good theoretical priors will play a crucial part in strengthening our data analysis, improving our observational constraints, and guiding our theories of gravity.
Speaker: | Scott Melville (University of Cambridge) |
Material: | Slides |
I argue for the existence of topologically stable, finite mass monopoles within Born-Infeld extension of the standard model and discuss some phenomenological and cosmological implications.
Speaker: | Mr. Suntharan Arunasalam (University of Sydney) |
Material: | Slides |
Strong coupling in Higgs inflation at high energies hinders a joint description of inflation, reheating and low-energy dynamics. The situation may be improved with a proper UV completion of the model. A well-defined self-consistent way is to introduce an R^2-term into the action. In this modified model the strong coupling scale returns back to the Planck scale, which justifies the use of the perturbative methods in studies of the model dynamics after inflation. We investigate the reheating of the post-inflationary Universe, which involves two highly anharmonic oscillators strongly interacting with each other: homogeneous Higgs field and scalaron. We observe that in interesting regions of model parameter space these oscillations make longitudinal components of the weak gauge bosons tachyonic, triggering instant preheating at timescales much shorter than the Hubble time. The weak gauge bosons are heavy and decay promptly into light Standard Model particles, ensuring the onset of the radiation domination era right after inflation.
Speaker: | Mr. Chris Shepherd (The University of Manchester) |
Material: | Slides |
We study the consequences of (beyond) positivity of scattering amplitudes in the effective field theory description of the Higgs-Dilaton inflationary model. By requiring the EFT to be compatible with a unitary, causal, local and Lorentz invariant UV completion, we derive constraints on the Wilson coefficients of the first higher order derivative operators. We show that the values allowed by the constraints are consistent with the phenomenological applications of the Higgs-Dilaton model.
Speaker: | Dr. Inar Timiryasov (EPFL) |
Material: | Slides |
In arXiv:1904.12783, we showed through numerical simulations of a minimally coupled massive Klein-Gordon scalar field that it is possible to grow "hair" on a Schwarzschild black hole if one assumes a periodically time-varying (but spatially homogeneous) background. We saw a non-trivial profile emerge on a timescale related to the mass of the black hole, both with and without backreaction of the field on the metric. The results are particularly relevant for scalar-tensor theories of gravity and dark matter models consisting of a massive scalar, e.g. axions. Our simulations are also a first step in studying the impact of such a background on a binary merger, potentially resulting in a imprint on the gravitational wave merger signal.
Speaker: | Dr. Katy Clough (Oxford University) |
Material: | Slides |
Conveners: | Prof. Srubabati Goswami (Physical Research Laboratory/Imperial College London) |
Location: | Schuster ( Moseley Lecture Theatre ) |
LUX-ZEPLIN (LZ) is a xenon-based direct detection dark matter experiment, currently under construction about one mile below ground at the Sanford Underground Research Facility in the USA. The experiment's 5.6 tonnes of fiducial volume will be a 22-fold increase over its predecessor, LUX. This will allow the experiment to be sensitive to 40 GeV WIMPs with spin-independent cross-sections as low as 1.6x10^{-48} cm^2 at 90% C.L. following an exposure of 1000 live days, which will begin in 2020. LZ is designed around a two-phase xenon time projection chamber, contained in an ultra-low background titanium cryostat, and surrounded by several auxiliary veto systems including an outer liquid xenon layer and a gadolinium-doped liquid scintillator detector. This presentation gives an overview of the experiment, its current status and timeline, and the predicted sensitivity and backgrounds.
Speaker: | Mr. Benjamin Krikler (Univeristy of Bristol) |
Material: | Slides |
The mirror dark matter model accommodates dark matter in a hidden sector which is isomorphic to the Standard Model, containing mirror partners of Standard Model particles. A weak kinetic mixing interaction allowed by the symmetry between the two sectors gives interactions between charged ordinary and mirror particles. The LUX dark matter direct detection experiment would be sensitive to electron recoils from interactions of incoming mirror electrons with atomic electrons in the liquid xenon. The model for incoming mirror electrons is complicated by shielding effects from captured mirror dark matter within the Earth. Here the first calculations of the mirror electron scattering rate in liquid xenon, accounting for shielding, are carried out. The first direct detection search for mirror dark matter is then conducted, using 95 days of LUX data from 2013. With no evidence for an electron recoil signal, we rule out temperatures above 0.3 keV within the assumptions made for this model. Below this temperature we place a 90% confidence limit on the kinetic mixing parameter.
Speaker: | Ms. Elizabeth Leason (University of Edinburgh) |
Material: | Slides |
In this talk, we introduce a new mechanism of direct baryogenesis by baryon number violating effective operator which is analogous to neutron-antineutron oscillation after electroweak symmetry breaking. Sufficient amount of the baryon asymmetry can be produced through the flavor oscillation after inflaton/moduli decay by the operator during the energy loss processes. We also suggest the mechanism could be searched by terrestrial experiments such as neutron-antineutron oscillation experiments as well as collider experiments.
Speaker: | Dr. Hiroyuki Ishida (KEK) |
Material: | Slides |
The XENON collaboration has an experimental program consisting of a series of liquid-xenon time-projection chambers to directly detect our galactic dark matter halo. The most recent detector XENON1T is currently the most sensitive direct detection experiment to date at the electroweak scale, while still being sensitive to new physics processes such as the double-electron capture process that we recently discovered. On the near horizon is the XENONnT experiment, who's physics program is similar to that of the UK-participating LZ, which is currently being commissioned. Additionally, other physics programs such as neutrinoless double-beta decay are being explored. I'll explain what XENON1T found and what it didn't find, while explaining where we expect to be in the coming few years.
Speaker: | Prof. Christopher Tunnell (Rice) |
Material: | Slides |
Conveners: | Prof. Bohdan Grzadkowski (University of Warsaw) |
Location: | Schuster ( Bragg Lecture Theatre ) |
The Inert Doublet Model is an intriguing extension of the SM scalar sector. It is a two Higgs doublet model with a discrete Z_2 symmetry, that renders the lightest particle from the second doublet stable and therefore provides a good dark matter candidate. Current constraints on the model as well as discovery prospects at current and future searches will be discussed, with a special emphasis on future $e^+e^-$ machines with center-of-mass energies up to 3 TeV (CLIC). A large set of proposed benchmark points promise to be testable with high significances.
Speaker: | Jan Kalinowski (University of Warsaw) |
Material: | Slides |
We consider the Maximally Symmetric Two-Higgs Doublet Model (MS-2HDM) in which the so-called Standard Model (SM) alignment can be naturally realised as a consequence of an accidental SO(5) symmetry in the Higgs sector. This symmetry is broken (i) explicitly by renormalization-group (RG) effects and (ii) softly by the bilinear scalar mass term $m^2_{12}$. We find that in the MS-2HDM all quartic couplings can unify at large RG scales $\mu_X \sim 10^{11}$-$10^{20}$ GeV. In particular, we show that quartic coupling unification can take place in two different conformally invariant points, where all quartic couplings vanish. We perform a vacuum stability analysis of the model in order to ensure that the electro-weak vacuum is sufficiently long-lived. The MS-2HDM is a minimal and very predictive extension of the SM governed by only three additional parameters: the unification scale $\mu_X$, the charged Higgs mass $M_{h^{\pm}}$ (or $m^2_{12}$) and $\tan\beta$, which allow one to determine the entire Higgs sector of the model. In terms of these input parameters, we present illustrative predictions of misalignment for the SM-like Higgs-boson couplings to the $W^\pm$ and $Z$ bosons and, for the first time, to the top and bottom quarks.
Speaker: | Dr. Neda Darvishi (University of Manchester) |
Material: | Slides |
In this talk we present the comprehensive numerical analyses and the analytic one-loop results for the low-energy observables, $(g-2) _\mu$, $\mu \to e \gamma$, and $\mu \to e$ conversion in the Minimal R-symmetric Supersymmetric Standard Model (MRSSM). The interplay between the three observables is investigated as well as the parameter regions with large $(g−2) _\mu$. A striking difference to the MSSM is the absence of $\tan\beta$ enhancements; however we find smaller enhancements governed by MRSSM-specific R-Higgsino couplings $\lambda _d$ and $\Lambda _d$. As a result we find significant contributions to $(g-2) _\mu$ only in a small parameter space with several SUSY masses below 200 GeV, compressed spectra and large $\lambda _d$, $\Lambda _d$. In this parameter space there is a correlation between all three considered observables. In the parameter region with small $(g-2) _\mu$ the SUSY masses can be larger and the correlation between $\mu \to e \gamma$ and $\mu \to e$ conversion is weak. Therefore already COMET Phase 1 has a promising sensitivity to the MRSSM. Ref.: arXiv:1902.06650 (submitted to JHEP)
Speaker: | Dr. Hyejung Stoeckinger-Kim (TU Dresden) |
Material: | Slides |
The possibility of a light stop mass less then 800 GeV is conflicted with the stability of electroweak vacuum in the context of restricted models such as CMMC. In this work, we consider the most general class possible of soft super symmetry breaking terms that can be added to the MSSM. We discuss the impact of non-standard soft breaking terms on the light stop sector. We show these terms lead to light stop mass which is consistent with the stability of electroweak vacuum.
Speaker: | Dr. Ahmad Farzaneh kord (Hakim Sabzevari University) |
We study the relation between the supersymmetry breaking patterns and the gauge couplings, prepotential of four-dimensional $\mathcal{N}=2$ gauged supergravity. The model contains multiple (Abelian) vector multiplets and a single hypermultiplet which parametrizes SO$(4,1)/{\rm{SO}}(4)$ coset. We derive the expressions of two gravitino masses under the general gauging based on the embedding tensor formalism, and discuss their behaviors in some concrete models. Our approach would be important when we discuss the relation with the flux compactification, and the application to particle and cosmological phenomenology.
Speaker: | Dr. Shuntaro Aoki (Waseda University) |
Material: | Slides |
Conveners: | Dr. Subodh Patil (Niels Bohr Institute) |
Location: | Schuster ( Rutherford Lecture Theatre ) |
Deviations of the CMB spectrum from a black-body are a powerful probe of the three-point function of curvature perturbations. Dissipation of acoustic waves in the photon-electron-baryon fluid heats the plasma: the heating is not balanced by an appropriate change in photon number, and a Bose-Einstein spectrum is formed. A non-zero three-point function of curvature perturbations makes the heating rate spatially dependent, so that the observed chemical potential in the sky will be anisotropic and correlated with large-scale temperature fluctuations. In this talk I discuss how the angular correlation of temperature anisotropies and spectral distortions is insensitive to contamination from late-time projection effects (unlike other observables like the CMB temperature bispectrum), making it an excellent, albeit futuristic, probe of primordial non-Gaussianity.
Speaker: | Mr. Giovanni Cabass (Max Planck Institute for Astrophysics) |
Material: | Slides |
Based on numerical lattice simulations, I discuss the impact of the geometrical destabilization of inflation on the inflationary trajectory and show, that it can significantly change the inflationary predictions. Geometrical destabilization is a phenomenon in which the non-inflationary degrees of freedom are destabilized due to negative curvature of the fields space manifold affecting the evolution of the inflaton condensate. Previous analyses of geometrical destabilization relied on linear perturbation theory and did not include backreaction in a consistent way. My results are the first step towards better understanding of this phenomenon and show that it can cause the second prolonged period of inflation.
Speaker: | Michal Wieczorek (Warsaw University) |
Material: | Slides |
We find a class of solutions for a homogeneous and isotropic universe in which the initially expanding universe stops expanding, experiences contraction, and then expands again (the "bounce"), in the framework of Einstein gravity with a real scalar field without violating the null energy condition nor encountering any singularities. Two essential ingredients for the bouncing universe are the positive spatial curvature and the scalar potential which becomes flatter at large field values. Depending on the initial condition, either the positive curvature or the negative potential stops the cosmic expansion and begins the contraction phase. The flat potential plays a crucial role in triggering the bounce. After the bounce, the flat potential naturally allows the universe to enter the slow-roll inflation regime, thereby making the bouncing universe compatible with observations. If the e-folding of the subsequent inflation is just enough, a positive spatial curvature may be found in the future observations. Our scenario nicely fits with the creation of the universe from nothing, which leads to the homogeneous and isotropic universe with positive curvature. As a variant of the mechanism, we also find solutions representing a cyclic universe.
Speaker: | Dr. Takahiro Terada (KEK) |
Material: | Slides |
Inflation and dark energy share many essential properties. I will show that these two eras can be easily unified into a common framework based on scale invariance. I will present the associated cosmological history and discuss how the inclusion of non-minimally coupled spectator fields may lead to the spontaneous symmetry breaking of internal symmetries and its eventual restoration at the onset of radiation domination. This sequence of events comes together with a rich phenomenology involving the generation of short-lived topological defects that tend to produce gravitational waves. The resulting power spectrum depends on the duration of the heating process and it is potentially detectable, providing a test on the existence of non-minimal couplings to gravity and on the characteristic energy scale of post-inflationary physics.
Speaker: | Dr. Rubio Javier (Helsinki Institute of Physics) |
Material: | Slides |
Observations have offered strong support for the theory of inflation, but many details of the physics of the early Universe are still unknown. An observation of primordial isocurvature modes would change our view of the early Universe and point towards multi-field inflation. In this talk, I will describe some recent work towards the calculation of second-order effects from isocurvature modes,focussing on the intrinsic bispectrum of the CMB. I will show the effects of general isocurvature modes to be small, but that a large enhancement is found for compensated isocurvature modes, given their large potential amplitude. The sensitivity of these second-order effects to this compensated mode allows us to severely constrain its amplitude using the non-observation of the predicted bispectrum.
Speaker: | Pedro Carrilho (Queen Mary University of London) |
Material: | Slides |
Convener: | Prof. Daniel Litim (University of Sussex) |
Location: | Rutherford theatre |
Convener: | Prof. Masahito Yamazaki (Kavli IPMU, University of Tokyo) |
Speaker: | Prof. Mikhail Shaposhnikov (EPFL) |
Material: | Slides |
Speaker: | Prof. Panagiota Kanti (University of Ioannina) |
Material: | Slides |
Speaker: | Prof. Neil Turok (Perimeter Institute for Theoretical Physics) |
Material: | Slides |
Conveners: | Prof. Christopher Tunnell (Rice) |
Location: | Schuster ( Moseley Lecture Theatre ) |
Since the early 1980s, Feynman and others discussed how quantum systems could be efficiently simulated through tools of quantum computation. Such quantum simulations may in fact turn out to be the only way certain phenomena experimentally difficult to realise can be studied, one such phenomena being neutrino oscillations. Though neutrinos are predicted by the standard model to be massless and weakly interacting, experiments have established the contrary, with neutrino oscillations further implying that they can change flavour as a consequence. In addition to pointing towards Physics beyond the Standard Model in this way, neutrino oscillations have also explained physical phenomena well and were key to solving the Solar neutrino problem. Interestingly, work by Molfetta in 2016 and Mallick in 2017 have shown how Quantum Random Walks (QRWs) can be used to not only simulate neutrino oscillations but also give insight into their underlying Physics. QRWs are quantum analogues of classical random walks, and as universal algorithms are an important tool in quantum information theory. They can also be used to simulate quantum systems and a heuristic overview of how QRWs can indeed simulate properties of neutrino oscillations is presented.
Speaker: | Mr. Farhan Chowdhury (Aberystwyth University) |
Material: | Slides |
The origin of the neutrino mass is still an open problem in physics and many efforts are being made to solve it. Among the possible solutions, the simplest ones involve an extension of the Standard Model, where new singlet fermions are added. Symmetry-protected variants of the seesaw mechanism, like the Inverse Seesaw, could explain the existence of light-neutrino masses while also providing observable signatures of Heavy Neutral Leptons (HNLs) in a range of upcoming neutrino beam experiments. In this talk, I will discuss the phenomenology of sterile neutrinos arising from low-scale neutrino mass models and the implications of a realistic mass model on the search for HNL. I will focus in particular on the impact on the signal of the strong polarisation effects in the beam for Majorana and (pseudo-)Dirac states, providing formulae to incorporate these in both production and decay. I will then talk about signatures for discovery of HNL and signatures of lepton number violation that could be searched for in beam dump experiment, tailoring the study to the upcoming DUNE experiment.
Speaker: | Mr. Tommaso Boschi (Durham University, IPPP - Queen Mary University of London) |
Material: | Slides |
Neutrinoless double beta decay can significantly help to shed light on the issue of non-zero neutrino mass, as observation of this lepton number violating process would imply neutrinos are Majorana particles. However, the underlying interaction does not have to be as simple as the standard neutrino mass mechanism. The entire variety of neutrinoless double beta decay mechanisms can be approached effectively. In this talk I will focus on a theoretical description of short-range effective contributions to neutrinoless double beta decay, which are equivalent to 9-dimensional effective operators as well as a novel mode with a Majoron-like scalar particle emitted in the decay.
Speaker: | Dr. Frank Deppisch (University College London) |
Material: | Slides |
Super-Kamiokande (SK) is a large-scale water Cherenkov neutrino detector located 1km underground in Gifu prefecture, Japan. Credited, alongside the SNO experiment, for the discovery of neutrino oscillation, SK has a rich history of neutrino physics. Refurbishment work was recently completed to prepare SK for its next phase: SK-Gd. This upgrade consists of doping SK with gadolinium, which allows for easier tagging of positrons from inverse beta decay through the coincidence detection of the 8 MeV gamma cascade from neutron capture on Gd. This will greatly reduce the background for low energy electron anti-neutrino events, allowing for analysis of never-before detected Supernova Relic Neutrinos, among other exciting sources. The status of the SK-Gd project and its physics goals will be presented.
Speaker: | Mr. Alexander Goldsack (University of Oxford/Kavli IPMU) |
Material: | Slides |
Conveners: | Mr. Daniele Teresi (Università di Pisa) |
Location: | Schuster ( Rutherford Lecture Theatre ) |
In the standard picture of cosmology, the Universe began at the Big Bang; the Big Bang itself is a singularity where the laws of physics break down. A quantum theory of gravity should resolve this singularity and help in understanding the initial state of the Universe needed to account for present observations. I will present some progress towards this goal in the group field theory approach to quantum gravity, using the idea of a universe formed as a "condensate", i.e. a very homogeneous quantum configuration, from a large number of discrete building blocks of geometry. I will show how this setting produces new cosmological models without an initial singularity, and how it can suggest a new mechanism for the generation of cosmological perturbations through quantum gravity vacuum fluctuations.
Speaker: | Dr. Steffen Gielen (University of Nottingham) |
Material: | Slides |
We revisit the effects of an early matter dominated era on gravitational waves induced by scalar perturbations. An early matter dominated era is a period during which the energy density of a massive field dominates the Universe before the reheating. We carefully take into account the evolution of the gravitational potential, source of the gravitational waves, around the transition from an early matter dominated era to the radiation dominated era. As a result, we find that the induced gravitational waves can be suppressed or enhanced depending on the timescales of the transition. This talk will be based on our papers, arXiv:1904.12878 and 1904.12879.
Speaker: | Mr. Keisuke Inomata (ICRR, The University of Tokyo) |
Material: | Slides |
The next generation detectors will verify, or at least constraint high energy phenomena, predicted by the vast variety of inflationary scenarios [1]. If a circularly polarized gravitational wave signal is detected, would point to the existence of parity breaking physics [2]. Here we consider, possible realizations of the effective field theory (EFT) of scalar-tensor gravity [3], which could offer a rich phenomenology. We introduce modifications to gravity which, at leading order, change the dispersion relation of gravitons [4]. The action is extended to include derivatively coupled interactions, where time-diffeomorphism invariance and parity are broken [5]. The higher-curvature coefficients are expressed in terms of relative parameters scaled by negative powers of a small speed of sound. This pushes their values into the "UV sensitive" regime where the energy scales supressing these corrections are well below the scale of the reduced Planck mass, leading to parametrically large chiral tensor fluctuations. We show that the inclusion of additional higher-derivative operators helps to cure instabilities that are otherwise unavoidable in Chern-Simons gravity [6], and derive constraints that ensure healthy solutions to the equations of motion. Finally, we discuss the effect of a disformal transformation on our system and look at other possible generalizations of scalar-tensor gravity from the EFT point of view. References [1] S. Shandera et al, "Probing the origin of our Universe through cosmic microwave background constraints on gravitational waves", [arXiv:astro-ph/1903.04700v1] (2019) [2] S. Saito, K. Ichiki and A. Taruya, "Probing polarization states of primordial gravitational waves with CMB anisotropies", JCAP 0709 (2007) 002 [3] A. R. Solomon, M. Trodden, "Higher-derivative operators and effective field theory for general scalar-tensor theories", JCAP 1802 (2018) 031 [4] T. Kobayashi, M. Yamaguchi, J. Yokoyama, "Generalized G-inflation: Inflation with the most general second-order field equations", Prog.Theor.Phys. 126 (2011) 511 [5] S. Weinberg, "Effective field theory for inflation", Phys.Rev. D 77 (2008) [6] S. Dyda, E. E. Flanagan, M. Kamionkowski, "Vacuum Instability in Chern-Simons Gravity", Phys.Rev. D 86 (2012) 124031
Speaker: | Maria Mylova (Swansea University) |
Material: | Slides |
In the Standard Model, electroweak symmetry breaking is a crossover. In many extensions, the phase transition can be of first order – even strongly so. The resulting phase transition can then be a substantial source of gravitational waves. For a phase transition at or around the electroweak scale, these gravitational waves may be detectable by future or planned missions, such as LISA. This can indirectly provide a probe of particle physics beyond the Standard Model, complementary to future colliders. In this talk I will discuss the physics that will make this possible and present some new simulation results for strong phase transitions, showing that vorticity is generated during the phase transition and substantial reheating can occur in front of the bubbles. This slows them down and, in certain cases, can suppress the generation of gravitational waves from the phase transition.
Speaker: | David Weir (University of Nottingham) |
Material: | Slides |
Could gravitational waves open the door to observe quantum gravity? In this talk I provide an initial answer, and show that results are quite promising. Recent developments in the effective field theory of quantum gravity uncovered the low-energy structure of the effective action in curved space. The long-distance portion of quantum loops manifests in a set of parameter-free non-local operators, which are fully captured by the effective theory. I quantify the effects of these non-local corrections on the gravitational radiation emitted by a binary source. I present a self-consistent perturbative method to solve the non-local theory, that crucially admits a causal prescription to be imposed on the wave solutions. I employ a tensor-vector-scalar decomposition of the metric perturbations to reveal the propagating gauge-invariant degrees of freedom. The central results show that quantum gravity inevitably excites the four modes of metric perturbations which are pure gauge in general relativity, namely the transverse vector and scalar modes. I compute the waveforms of the extra propagating modes, in addition to the modification to the transverse-traceless metric perturbations. The new modes have mass and travel with sub-luminal group velocity.
Speaker: | Dr. Basem Elmenoufi (University of Sussex) |
Conveners: | Prof. Qaisar Shafi (University of delaware) |
Location: | Schuster ( Bragg Lecture Theatre ) |
The Two Higgs Doublet Model (2HDM) is an extension of the Standard Model (SM) of particle physics in which one additional complex scalar doublet is introduced into the theory. The extension to a non-minimal Higgs sector produces several new features beyond the SM. One such feature is that the 2HDM can have non-trivial vacuum topology predicting 3 distinct domain wall solutions from the breaking of 3 accidental symmetries at the electroweak scale. We present numerical kink solutions for all three cases. In particular, we discuss the dependence of features in these kink solutions on the physical parameters of the model, i.e. Higgs masses and mixing angles. We also present numerical simulations of the evolution of domain wall networks in these models for certain parameter sets consistent with current experimental constraints. We discuss the scaling behaviour of these networks and connections to the interaction of kinks in these models. These results provide a view into the phenomenology of 2HDM domain walls as a cosmological probe of extended Higgs sectors and their potential to provide complementary constraints to particle physics experiments.
Speaker: | Mr. Dominic Viatic (University of Manchester) |
Material: | Slides |
We investigate the baryon asymmetry in the supersymmetry Dine-Fischler-Srednicki-Zhitnitsky axion model without R-parity. It turns out that the R-parity violating terms economically explain the atmospheric mass-squared difference of neutrinos and the appropriate amount of baryon asymmetry through the Affleck-Dine mechanism. In this model, the axion is a promising candidate for the dark matter and the axion isocurvature perturbation is suppressed due to the large field values of Peccei-Quinn fields. Remarkably, in some parameter regions explaining the baryon asymmetry and the axion dark matter abundance, the proton decay will be explored in future experiments.
Speaker: | Mr. Kensuke Akita (Tokyo Institute of Technology) |
Material: | Slides |
Transition amplitudes describing dark-matter annihilation processes through a resonance may become highly inaccurate close to a production threshold if a Breit-Wigner propagator with a constant width is used. To partially overcome this problem, the BW propagator needs to be modified by including a momentum dependent decay width. However, such an approach to resonant transition amplitudes generically suffers from gauge artefacts that may also give rise to a bad or ambiguous high-energy behaviour of the amplitudes. We address the two problems of gauge dependence and high-energy unitarity within a gauge-independent framework of resummation implemented by the so-called e Technique. We study DM annihilation via scalar resonances in a gauged U(1)_X complex-scalar extension of the Standard Model that features a massive stable gauge field which can play the role of the DM. We find that the predictions for the DM abundance may vary significantly from previous studies using Breit-Wigner ansatz and propose an alternative simple approximation which leads to the correct DM phenomenology.
Speaker: | Mateusz Duch (University of Warsaw) |
Material: | Slides |
Classification of Dark Matter (DM) models is the key for the consistent exploration of DM model space and comprehensive probe of DM nature at current and future experiments. We perform systematic classification of Minimal Consistent DM (MCDM) models -- gauge invariant, renormalisable and anomaly free models -- in terms of DM and mediator weak multiplets. MCDM represents a natural building block for any BSM theory which includes DM. We consider two cases: 1) when only SM fields play the role of the mediator for DM multiplet; 2) when there is an additional mediator multiplet -- odd or even under the symmetry, providing DM stability. We explore the phenomenology of new representative model found in this classification. This model has a two-component dark-sector containing an odd singlet Dirac fermion alongside an accidentally stable even pseudo-scalar mediator. The model exhibits a non-trivial interplay between two components of DM contributing to relic density and can be probed at direct, indirect DM search experiments as well as at the LHC and future FCC-hh colliders.
Speaker: | Mr. Daniel Locke (University of Southampton) |
Material: | Slides |
We study in detail simple extension of the freeze-in mechanism based on kinematically forbidden production of dark matter through plasma effects. Focusing on Higgs portal model, where the dark matter is produced via forbidden decays of a scalar coupled to the Higgs, current and future collider, cosmological, and astrophysical probes are considered.
Speaker: | Dimitrios Karamitros (NCBJ) |
Material: | Slides |
Conveners: | Prof. Nikolaos Mavromatos (King's College London) |
Location: | Schuster ( Annex: Bell Burnell Lecture Theatre ) |
Matrix Inflation, or M-flation in brevity, is a string theory motivated model of inflation that uses the matrix degrees of freedom of a stack of D3 branes in appropriate fluxes to realize inflation. In its minimal format, inflatons are minimally coupled to gravity. In order to match M-flation with observation, one needs a large number of D3-branes that can backreact on the background geometry. Part of the inflaton potential, in which the presumed SU(2) configuration of the matrices is a local attractor and can sustain eternal inflation has been ruled out by PLANCK data. The spectator fields, whose masses depend on the effective inflaton, cannot be used as preheat fields if inflation happens in this region of potential too. I show how the non-Minimal version of the model, which we call non- \mathbb{M}-flation can overcome all the aforementioned problems. I suggest how this non-minimal coupling can arise in the string theory setup.
Speaker: | Dr. Amjad Ashoorioon (Dr) |
Material: | Slides |
Quantum decay of false vacuum states via the nucleation of bubbles may have played an important role in the early history of our Universe. For example, in multiverse models that utilize false vacuum eternal inflation, the Big Bang of our observable Universe corresponds to one of these bubble nucleation events. Further, our observable Universe may have undergone a series of symmetry-breaking first-order phase transitions as it cooled, which may have produced a remnant background of gravitational waves. I will present results from a new real-time picture of false vacuum decay which, in contrast to existing semiclassical techniques, does not rely on classically forbidden tunneling paths. Lattice simulations are used to evolve initial realizations of fluctuations around the false vacuum forward in time via the classical equations of motion. In these simulations, we observe the false vacuum decay via the formation and subsequent expansion and coalescence of true vacuum bubbles. By sampling initial field realizations, we build up ensembles of these decay histories and empirically determine the bubble nucleation rate. The rates agree well with standard Euclidean techniques, which cannot provide a time-dependent description of the decay. Novel applications of our new approach include investigation of bubble-bubble correlation functions, decay of non-vacuum initial states, and the regime of rapid decays.
Speaker: | Dr. Jonathan Braden (CITA / University of Toronto) |
In this talk, we present whether the new ekpyrotic scenario can be embedded into ten-dimensional supergravity. We use that the scalar potential obtained from flux compactifications of type II supergravity with sources has a universal scaling with respect to the dilaton and the volume mode. Similar to the investigation of inflationary models, we find very strong constraints ruling out ekpyrosis from analyzing the fast-roll conditions. We conclude that flux compactifications tend to provide potentials that are neither too flat and positive (inflation) nor too steep and negative (ekpyrosis).
Speaker: | Dr. Kunihito Uzawa (Kwansei Gakuin University) |
Material: | Slides |
The effective field theory of cosmic inflation has been highly constrained by the swampland conditions recently. In brane inflation the Friedmann equation is modified to include an additional parameter λ called brane tension that modifies the slow-roll parameters such that the restrictive swampland conditions can be naturally evaded. We discuss superconformal α-attractor E-models that are consistent with distance conjecture and the further refined de Sitter conjecture. We derive an analytic formulae for n_s and r that approximates the accurate results very well. This class of models satisfies various consistency requirements and is also consistent with the Planck 2018 and BICEP2 observational constraints on n_s and r.
Speaker: | Mr. Mudassar Sabir (Huazhong University of Science and Technology, Wuhan, Hubei, China) |
4-dimensional Starobinsky model, whose action has a curvature squared R^2 term, is one of the most promising inflation models. However the origin of the higher curvature term is still unknown. From the viewpoint of high energy physics, higher curvature terms should appear as a series of curvature, i.e. there must exist R^m (2
Speaker: Mr. Yu Asai (Waseda university) Material: Slides
Conveners: | Prof. Archil Kobakhidze (The University of Sydney) |
Location: | Schuster ( Blackett Lecture Theatre ) |
We investigate the potential of the Large Hadron Collider (LHC) to probe one of the most compelling Beyond the Standard Model (BSM) frameworks --- Walking Technicolor (WTC), involving strong dynamics and having a slowly running (walking) new strong coupling. For this purpose we use recent LHC Run2 data to explore the full parameter space of the minimal WTC model using dilepton signatures from heavy neutral Z′ and Z′′ resonances predicted by the model. This signature is the most promising one for discovery of WTC at the LHC for the low-intermediate values of the g-tilde coupling -- one of the principle parameters of WTC. We have demonstrated complementarity of the dilepton signals from both resonances, have established the most up-to-date limit on the WTC parameter space, and provided projections for the the LHC potential to probe the WTC parameter space at higher future luminosities and upgraded energy. We have explored the whole four-dimensional parameter space of the model and have found the most conservative limit on the WTC scale MA above 3 TeV for the low values of g-tilde which is significantly higher than previous limits established by the LHC collaborations.
Speaker: | Ms. Azaria Coupe (Univeristy of Southampton) |
Material: | Slides |
Precision electroweak data, a light higgs and LHC searches for new spin one particles are all very constraining on technicolor models. We use a holographic model of walking techicolor (WTC) gauge dynamics, tuned to produce a light higgs and low S parameter, to estimate the range of possible vector(ρ) and pseudo-vector(A) resonance masses and couplings as a function of the number of colours and the number of flavours of techni-singlet and techni-doublet quarks. The resulting models predict techni-hadron masses and couplings above the current limits from dilepton resonance searches at the LHC because their masses are enhanced by the strong coupling extending into the multi-TeV range, while couplings to Standard Model fermions are partly suppressed. The models emphasize the contortions needed to continue to realize technicolor, {the need to explore new signatures beyond dilepton for LHC and also motivate a 100 TeV proton collider.
Speaker: | Prof. Nicholas Evans (University of Southampton) |
Material: | Slides |
I discuss findings from my recent comparison of Bayesian and frequentist approaches to resonance searches (1902.03243). I introduce a counting experiment based on a search for the Higgs boson from which I generate pseudo-data. With that pseudo-data, I contrast the evolution of the $p$-value and posterior as we accumulate data and directly compare global $p$-values and the posterior of the background model. I find that in this toy problem $p$-values are typically smaller than the posterior by one or two orders of magnitude. I discuss the implications of this result for our interpretation of anomalies in resonance searches and searches for new physics in general.
Speaker: | Dr. Andrew Fowlie (Nanjing Normal University) |
Material: | Slides |
I discuss the possibility of exponentially large cross-sections in field theories. Such effects were recently suggested to be present in theories with higgs mechanism, leading to exciting effects both for experimental observation and theoretical properties of the QFT. I will comment on the problems arising if this effect is really present, and discuss why it is hard to expect any exponential cross-sections in real world.
Speaker: | Dr. Fedor Bezrukov (The University of Manchester) |
Material: | Slides |
Conveners: | Prof. Roger Barlow (University of Huddersfield) |
Location: | Schuster ( Blackett Lecture Theatre ) |
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. With this data set, Belle II will be able to measure the Cabibbo-Kobayashi-Maskawa (CKM) matrix, the matrix elements and their phases, with unprecedented precision and explore flavor physics with $B$ and charmed mesons, and $\tau$ leptons. Belle II has also a unique capability to search for low mass dark matter and low mass mediators. From February to July 2018, the machine has completed a commissioning run, achieved a peak luminosity of $5.5\times 10^{33}$ cm$^{-2}$s$^{-1}$, and Belle II has recorded a data sample of about 0.5 fb$^{-1}$. Regular operations, with full detector, have started in March 2019. In this presentation, we will review the status of the Belle II detector, the results from the early data, and the prospects for the study of rare decays, in the quest of uncovering New Physics.
Speaker: | Alberto Martini (University & INFN Roma Tre) |
Material: | Slides |
Some physics scenarios beyond the Standard Model of particle physics restore right-handed weak currents, which would manifest themselves in the polarization of the photon produced in $b\to s\gamma$ transitions. Due to the $V-A$ structure of the quark-$W$ coupling in the Standard Model, this polarization is strongly correlated with the flavour of the b-quark and suppresses interference responsible for time-dependent $CP$ violation in $B\to K_{res}\gamma$ decays. Observing sizable values of time-dependent asymmetries in these decays would therefore represent a null-test of the Standard Model. The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has completed a commissioning run, achieved a peak luminosity of $5.5\times 10^{33}$ cm$^{-2}$s$^{-1}$, and Belle II has recorded a data sample of about 0.5 fb$^{-1}$. Main operation of SuperKEKB has started in March 2019. In this presentation we show how the final Belle II data set will allow to evaluate the time-dependent asymmetries for the final states $K_S^0\pi^0\gamma$ and $K_S^0\pi^+\pi^-\gamma with statistical uncertainties at the level of a few $10^{-2}$. As a preparatory exercise, we describe the first measurement of the B-lifetime with the early Belle II data, which already allows to understand accurate modelling of the time resolution as an essential ingredient.
Speaker: | Dr. Olga Verbitskaja (Institute of Nuclear Physics PAN, Warsaw) |
Material: | Slides |
The decay K+→π+vv , with a very precisely predicted branching ratio of less than 10exp[-10], is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at the CERN SPS is designed to measure the branching ratio of the K+→π+vv ̅ with a decay-in-flight technique. NA62 took data so far in 2016-2018. Statistics collected in 2016 allowed NA62 to reach the Standard Model sensitivity for K+→π+vv ̅, entering the domain of 10exp[-10] single event sensitivity and showing the proof of principle of the experiment. Thanks to the statistics collected in 2017, NA62 surpasses the present best sensitivity. The analysis strategy is reviewed and the preliminary result from the 2017 data set is presented. A large sample of charged kaon decays into final states with multiple charged particles was collected in 2016-2018. The sensitivity to a range of lepton flavor and lepton number violating kaon decays provided by this data set improves over the previously reported measurements. Results from the searches for these processes with a partial NA62 data sample are presented.
Speaker: | Dr. Jacopo Pinzino (CERN) |
Material: | Slides |
The features of the NA62 experiment at the CERN SPS – high-intensity setup, trigger-system flexibility, high-frequency tracking of beam particles, redundant particle identification, and high-efficiency photon vetoes – make NA62 particularly suitable to search for long-lived, weakly-coupled particles within Beyond the Standard Model (BSM) physics, using kaon and pion decays as well as operating the experiment in dump mode. The NA62 sensitivity for searches of Dark Photons, Heavy Neutral Leptons and Axion-Like Particles are presented, together with prospects for future data taking at the NA62 experiment.
Speaker: | Dr. Monica Pepe (INFN Perugia) |
Material: | Slides |
Conveners: | Prof. Mikhail Shaposhnikov (EPFL) |
Location: | Schuster ( Annex: Bell Burnell Lecture Theatre ) |
It is a well-known fact that compact gravitating objects admit bound state configurations for massive bosonic fields. In this work we describe a new class of superradiant instabilities of axion bound states in neutron star magnetospheres. The instability arises from the mixing of axion and photon modes in the magnetic field of the neutron star which extract energy from the rotating magnetosphere. Unlike for black holes, where the dissipation required for superradiance is provided by an absorbative horizon, the non-hermitian dynamics in this work come from the resistivity in the stellar magnetosphere arising from a finite bulk conductivity.
Speaker: | Dr. Francesca Day (University of Cambridge) |
Material: | Slides |
If a component of dark matter is millicharged, dark matter-baryon scattering can induce large effects in the 21-cm global signal by cooling the baryons. This can be achieved without being excluded by other cosmological, astrophysical or terrestrial constraints. We point out two important effects which have been overlooked in previous analyses. First, introducing a dark interaction between the millicharged component and the neutral component of dark matter increases the heat capacity of the dark sector, making the cooling process more efficient at higher dark matter masses. Second, the scattering of millicharged dark matter off neutral hydrogen and helium is an important effect that may dominate the cooling of baryons during the cosmic dark ages. Due to a combination of these two effects, the anomalous 21-cm global signal observed by the EDGES collaboration can now be explained by a sub-percent millicharged component of dark matter with a mass as large as 50 GeV. Interestingly, the cross section required to fit this signal lies exactly in the allowed window for strongly interacting dark matter, in between the shielding regime of direct detection experiments and the current bounds from astrophysics and colliders.
Speaker: | Dr. Hongwan Liu (MIT) |
Material: | Slides |
Sterile neutrinos is one of the possible physics beyond the Standard Model motivated by neutrino oscillations. Stable at cosmological time-scale sterile neutrinos may serve as dark matter. Typically, with mass in keV range, the sterile neutrinos form Warm dark matter and radiatively decay in galaxies providing X-ray telescopes with a prominent signature. Extensive searches for the sterile neutrino dark matter significantly reduced viable regions in the model parameter space. However, the situation changes with just one new ingredient -- a scalar field with Yukawa coupling to the sterile neutrinos. This scalar modifies the sterile neutrino production in the early Universe. Depending on the scalar field dynamics it makes models with large(small) active-sterile mixing cosmologically viable(interesting)
Speaker: | Prof. Dmitry Gorbunov (INR RAS) |
Material: | Slides |
I will briefly explore the definition and limitations of the Cold Dark Matter (CDM) paradigm before introducing Generalised Dark Matter (GDM), an approach that subsumes the CDM paradigm. GDM facilitates well-defined model-independent observational constraints on the cosmological dark matter, including null tests of CDM. I will present some constraints that have been obtained using a combination of cosmological datasets, notably Planck, BAO and WiggleZ matter power spectrum data, including constraints on the equation of state and abundance of dark matter over 5 decades in redshift. An observational hint of beyond-CDM properties will be presented, along with a discussion of the importance of correctly modelling non-linear cosmological scales.
Speaker: | Dr. Daniel Thomas (JBCA, Manchester) |
Material: | Slides |
I am going to compare two simple models of dark matter (DM): a vector and a scalar DM model. Both models require the presence of two physical Higgs bosons h_1 and h_2 which come from mixed components of the standard Higgs doublet H and a complex singlet S. In the vector model, the extra U(1) symmetry is spontaneously broken by the vacuum of the complex field S. This leads to a massive gauge boson X_mu that is a DM candidate stabilized by the dark charge conjugation symmetry. On the other hand, in the scalar model the gauge group remains the standard one. The DM A is the imaginary component of S and the stabilizing symmetry is also the dark charge conjugation. In this case, in order to avoid spontaneous breaking, the U(1) symmetry is broken explicitly, but softly, in the scalar potential. In the scalar model the tree-level DM-nucleon scattering cross section vanishes in the limit of zero momentum-transfer. We have calculated the exact cross section in the zero momentum-transfer at the leading-order i.e., at the one-loop level of perturbative expansion. The possibility to disentangle the two models has been investigated.
Speaker: | Prof. Bohdan Grzadkowski (University of Warsaw) |
Material: | Slides |
Conveners: | Dr. Frank Deppisch (University College London) |
Location: | Schuster ( Moseley Lecture Theatre ) |
MicroBooNE, the Micro Booster Neutrino Experiment at Fermilab, is an 85-ton active mass liquid argon time projection chamber (LArTPC) located in the Booster Neutrino Beam at Fermilab. MicroBooNE is the first of three LArTPC detectors that form the Short-Baseline Neutrino (SBN) program at Fermilab, which has three main aims: to search for new physics, particularly eV-scale sterile neutrinos, to study neutrino scattering on argon, and to advance LArTPC technology that will be used in the Deep Underground Neutrino Experiment. This talk will review the science goals of the SBN program, with a particular focus on MicroBooNE and its most recent neutrino scattering measurements. As the largest liquid argon detector worldwide taking neutrino beam data, MicroBooNE provides a unique opportunity to investigate neutrino-argon scattering at O(1 GeV) energies, as well as an exciting demonstration of the potential of LArTPC detector technology to improve our current understanding of neutrino physics.
Speaker: | Dr. Stephen Dennis (University of Liverpool) |
The Pierre Auger Observatory is the largest detector for cosmic rays with energies above EeV. The Observatory has established a clear suppression of the fluxes of the highest energy particles, charged nuclei, which are expected to come from extragalactic sources. The contribution of photons and neutrinos from more exotic sources is strongly limited. Cosmic rays are detected through the extensive air showers produced by collisions at centre-of-mass energies that extend above those tested at the LHC. Detailed analyses of the showers are key to identify the primary particle types and also to test the modelling of high energy hadronic interactions. Indeed, the available models do not perfectly describe the collected data, and currently the Auger surface detectors are being upgraded to provide more direct information on the shower particles. This talk will focus on the shower physics analyses and their impact on cosmic ray and hadronic interaction studies.
Speaker: | Sofia Andringa (LIP) |
Material: | Slides |
Recently the MiniBooNE Collaboration has reported an anomalous excess in muon to electron (anti-)neutrino oscillation data. Combined with long-standing results from the LSND experiment this amounts to a 6.1 sigma evidence for new physics beyond the Standard Model. In this talk I discuss a framework with 3 active and 3 sterile neutrinos with altered dispersion relations that can explain these anomalies without being in conflict with the absence of anomalous neutrino disappearance in other neutrino oscillation experiments.
Speaker: | Prof. Heinrich Päs (TU Dortmund) |
Material: | Slides |
Heavy neutrinos appear in many models of neutrino masses and mixing. In this talk, I will present a new search strategy at hadron colliders based on dynamical jet vetoes. This increases the sensitivity of the trilepton + missing transverse energy search by an order of magnitude and allows future colliders to search for heavy neutrinos with a mass of 10 TeV and above.
Speaker: | Dr. Cedric Weiland (Pitt PACC, University of Pittsburgh) |
Material: | Slides |
Conveners: | Prof. Nicholas Evans (University of Southampton) |
Location: | Schuster ( Bragg Lecture Theatre ) |
The SHiP Collaboration has proposed a general-purpose experimental facility operating in beam dump mode at the CERN SPS accelerator with the aim of searching for light, long-lived exotic particles of Hidden Sector models. The SHiP experiment incorporates a muon shield based on magnetic sweeping and two complementary apparatuses. The detector immediately downstream of the muon shield is optimised both for recoil signatures of light dark matter scattering and for tau neutrino physics, and consists of a spectrometer magnet housing a layered detector system with heavy target plates, emulsion film technology and electronic high precision tracking. The second detector system aims at measuring the visible decays of hidden sector particles to both fully reconstructible final states and to partially reconstructible final states with neutrinos, in a nearly background free environment. The detector consists of a 50 m long decay volume under vacuum followed by a spectrometer and particle identification with a rectangular acceptance of 5 m in width and 10 m in height. Using the high-intensity beam of 400 GeV protons, the experiment is capable of integrating $2\times 10^{20}$ protons in five years, which allows probing dark photons, dark scalars and pseudo-scalars, and heavy neutrinos with GeV-scale masses at sensitivities that exceed those of existing and projected experiments. The sensitivity to heavy neutrinos will allow for the first time to probe, in the mass range between the kaon and the charm meson mass, a coupling range for which baryogenesis and active neutrino masses can be explained. The sensitivity to light dark matter reaches well below the elastic scalar Dark Matter relic density limits in the range from a few $\mbox{MeV/c}^2$ up to $\mbox{200 MeV/c}^2$. The tau neutrino deep-inelastic scattering cross-sections will be measured with a statistics a thousand times larger than currently available, with the extraction of the $F_4$ and $F_5$ structure functions, never measured so far, and allow for new tests of lepton non-universality with sensitivity to BSM physics. Following the review of the Technical Proposal, the CERN SPS Committee recommended in 2016 that the experiment and the beam dump facility studies proceed to a Comprehensive Design Study phase. These studies have resulted in a mature proposal submitted to the European Strategy for Particle Physics Update.
Speaker: | Dr. Oliver Lantwin (University of Zürich) |
Material: | Slides |
The possibility of a light charged Higgs boson H± that decays predominantly to quarks (cs and/or cb) and with a mass in the range 80 GeV ≤mH±≤90 GeV is studied in the context of Three-Higgs-Doublet Models (3HDMs). At present the Large Hadron Collider (LHC) has little sensitivity to this scenario, and currently the best constraints are from LEP2 and Tevatron searches. The branching ratio of H±→cb can be dominant in two of the five types of 3HDM, and we determine the parameter space where this occurs. The decay H±→cb has recently been searched for at the LHC for the first time, and with increased integrated luminosity one would expect sensitivity to the region 80 GeV ≤mH±≤90GeV due to the smaller backgrounds with respect to H±→cs decays.
Speaker: | Mr. Muyuan Song (University of Southampton) |
Material: | Slides |
Light dark matter coupled to quarks must be treated through the effective couplings to mesons, which is implemented through the chiral lagrangian. We find the expected photon spectrum from the decay of the hadrons. We compare to current and future observations, and show that there is a significant discovery reach for such models of light dark matter.
Speaker: | Prof. Arvind Rajaraman (Univ of California, Irvine) |
Material: | Slides |
We study the monopole dark matter (MDM) emerging from a spontaneous breakdown of non-abelian gauge symmetry in the hidden sector. We assume that this hidden MDM was produced as a topological defect during a second-order phase transition in the early universe, and its stability is guaranteed by the topological nature. In particular, we introduce an axion-like particle (ALP), which mediates the interactions between the hidden MDM and nucleus, and the configuration of the ALP field is affected by the Witten effect in the presence of the hidden monopole. We then compute the spin-dependent elastic cross-section of the hidden MDM scattering off a nucleon and compare it to the direct search experiments. To induce the Witten effect, the ALP has to couple to the hidden photons. As a consequence, the bounds coming from the beam-dump experiments and B meson decays for the ALP decay constant are changed. By considering those constraints, we find that the room for the hidden MDM is still large with a benchmark point which can satisfy the relic abundance of dark matter while solving the small-scale problems in galaxy formation.
Speaker: | Mr. Shu-Yu Ho (Tohoku University) |
Material: | Slides |
Conveners: | Dr. Rubio Javier (Helsinki Institute of Physics) |
Location: | Schuster ( Rutherford Lecture Theatre ) |
I will introduce the innovative HI intensity mapping technique, which can turn the SKA and its MeerkAT precursor into precision cosmology machines. My talk will then focus on synergies between radio intensity mapping and optical galaxy surveys (e.g. GBT and SDSS, Euclid and SKA).
Speaker: | Dr. Alkistis Pourtsidou (QMUL) |
Material: | Slides |
We consider a scalar field with a bottom-less linear potential, finding that cosmologies unavoidably end up with a crunch, even in scenarios compatible with the observed positive cosmological constant. Assuming that rebounces avoid singularities, this generates a new kind of multiverse: the universe undergoes cycles with different cosmological constants, all with finite lifetime regardless of the sign. This novel "temporal" multiverse avoids some of the usual ambiguities present in the standard "spatial" one. Moreover, if a "hiccupping" mechanism changes the vacuum energy by a small amount at each cycle, this dynamics selects a small vacuum energy and becomes the most likely source of universes with anthropically small cosmological constant. Its probability distribution could avoid the gap of 2 orders of magnitude that seems left by standard anthropic selection.
Speaker: | Mr. Daniele Teresi (Università di Pisa) |
Material: | Slides |
I summarise constraints on new forces in the dark sector, originating from interactions with a dark energy scalar field. For standard constant couplings, cosmological observations constrain any new forces between dark matter particles to be very small, which is a challenge for quintessence model building in string theory. Instead, I propose to consider coupling functions with possess a minimum at finite field values. The effective gravitational constant between dark matter particles grows with time and are consistent with observations of CMB anisotropies and large scale structures. Such couplings might also alleviate the tension between the swampland-de Sitter conjecture and the properties of the quintessence potential. Observational signatures of violations of the equivalence principle in the dark sector are expected in the non-linear regime on intermediate or small scales.
Speaker: | Prof. Carsten van de Bruck (University of Sheffield) |
Material: | Slides |
Several modern theories hypothesize that dark matter condenses to a superfluid phase around galaxies. If true, one key distinction from particle dark matter is dynamical friction, a process by which a massive perturber moving through a cloud of matter is slowed by the gravitational attraction to its own wake. I will describe the steady-state dynamical friction of a perturber moving through a superfluid condensate. Crucially, I will account for the tachyonic gravitational mass of sound waves (a consequence of the Jeans instability of the fluid cloud), as well as the “quantum pressure” of the gas. I will show this in two equivalent ways: (i) via a familiar approach in which one linearizes the fluid equations, and (ii) via a novel quasiparticle description of phonon radiation. Although subsonic perturbers are ordinarily unable to experience a drag force in a superfluid, surprisingly we will find that the Jeans instability modifies the dispersion relation enough to result in small, but non-vanishing, subsonic dynamical friction. This effect may be a key observable in distinguishing between particle and fluid models of dark matter.
Speaker: | Dr. Benjamin Elder (University of Nottingham) |
Material: | Slides |
We discuss the question of frame equivalence of scalar-tensor theories in the path integral approach. We find that due to diffeomorphism invariance of the background geometry, the path integral measure must depend non-trivially on the metric. Under a change of frames, this induces new finite pieces in the Quantum Effective Action that must be taken into account to preserve frame equivalence at the quantum level. These pieces might be of relevance to asses the dynamics of the Early Universe within certain inflationary models.
Speaker: | Dr. Mario Herrero-Valea (EPFL) |
Material: | Slides |
Convener: | Dr. Vasiliki Mitsou (IFIC Valencia) |
Speaker: | Prof. Alexei Smirnov (Max-Planck Institute for Nuclear Physics, Heidelberg, Germany) |
Material: | Slides |
Speaker: | Prof. Un-ki Yang (Seoul National University) |
Convener: | Dr. Nazila Mahmoudi (Lyon University) |
Location: | Rutherford theatre |
Speaker: | Prof. Jose W. F. Valle (Valencia U.) |
Material: | Slides |
Speaker: | Dr. Joseph Price (University of Liverpool) |
Material: | Slides |
Speaker: | Dr. Byeong Rok Ko (Institute for Basic Science (IBS) Center for Axion and Precision Physics Research (CAPP)) |
Material: | Slides |
Convener: | Prof. Manuel Drees (Bonn University) |
Location: | Rutherford theatre |
Speaker: | Prof. Marcela Carena (U Chicago/ Fermilab) |
Material: | Slides |
The magnetic monopoles are, among other theoretical arguments, motivated by the electric-magnetic symmetry of the Maxwell equations and the quantisation of the electric charge. The Large Hadron Collider offers an ideal opportunity to produce and detect these hypothetical particles in the low-mass regime. General-purpose experiments, such as ATLAS, as well as ones dedicated to the search for (meta-)stable particles, such as MoEDAL, complement each other in this quest. Resent search results from both experiments will be presented. Plans for looking for trapped magnetic monopoles in the decommissioned CMS beam pipe will be also discussed.
Speaker: | Dr. Vasiliki Mitsou (IFIC (CSIC-Univ. Valencia)) |
Material: | Slides |
Convener: | Prof. Panagiota Kanti (University of Ioannina) |
Location: | Rutherford theatre |
Speaker: | Prof. Pran Nath (Northeastern University) |
Material: | Slides |
Speaker: | Prof. Vincenzo Branchina (Catania U.) |
Material: | Slides |
Speaker: | Prof. Qaisar Shafi (University of delaware) |
Material: | Slides |
Conveners: | Dr. Andrey Pozdnyakov (RWTH) |
Location: | Schuster ( Blackett Lecture Theatre ) |
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Speaker: | Dr. Nazila Mahmoudi (Lyon University) |
Material: | Slides |
The observation of neutral long-lived particles at the LHC would reveal physics beyond the Standard Model and could account for the many open issues in our understanding of our universe. Long-lived particle signatures are well motivated and can appear in many theoretical constructs that address the Hierarchy Problem, Dark Matter, Neutrino Masses and the Baryon Asymmetry of the Universe. With the current experiments at the particle accelerators, no search strategy will be able to observe the decay of neutral long-lived particles with masses above ∼GeV and lifetimes at the limit set by Big Bang Nucleosynthesis (BBN), cτ∼10^7−10^8 m. The MATHUSLA detector concept (MAssive Timing Hodoscope for Ultra-Stable neutraL pArticles) will be presented. It can be implemented on the surface above ATLAS or CMS detectors in time for the high-luminosity LHC operations, to search for neutral long-lived particles with lifetimes up to the BBN limit. The large area of the detector allows MATHUSLA to make important contributions also to cosmic-ray physics. We will also report on the analysis of data collected by the test stand installed on the surface above the ATLAS detector, the on-going background studies, and plans for the MATHUSLA detector.
Speaker: | Audrey Kvam (University of Washington) |
Material: | Slides |
In this talk, we will discuss the current status and future prospects of a recently approved experiment to search for light new physics particles produced in the far-forward region of the LHC, namely FASER, the ForwArd Search ExpeRiment. FASER has been proposed to supplement traditional experimental programmes searching for heavy new physics particles in the high-pT region and, therefore, to increase the whole BSM physics potential of the LHC. On top of potentially far-reaching implications to BSM particle physics and cosmology, the newly proposed detector can also perform high-energy SM neutrino measurements.
Speaker: | Dr. Sebastian Trojanowski (University of Sheffield) |
Material: | Slides |
Motivated by possible theoretical extensions to the standard model, hidden photons (HP) are a candidate for the cold dark matter. Their possible masses cover a broad range, from 10^-12 to 10^6 eV/c^2[1]. Large scale direct detection experiments such as LUX-ZEPLIN (LZ), built primarily to detect WIMPs, are also sensitive to HP dark matter via the so-called hidden photoelectric effect in the keV/c^2-MeV/c^2 mass scale . This work presents the projected LZ sensitivity for hidden photon search in the 2-85 keV/c^2 mass range. [1] P.Arias, et al., JCAP06 (2012) 013, “WISPy cold dark matter”
Speaker: | Mrs. Athoy Nilima (University of Edinburgh) |
Material: | Slides |
Conveners: | Cumrun Vafa (Harvard University) |
Location: | Schuster ( Annex: Bell Burnell Lecture Theatre ) |
The Wilsonian renormalization group (RG) requires Euclidean signature. The conformal factor of the metric then has a wrong-sign kinetic term, which has a profound effect on its RG properties. In particular around the Gaussian fixed point, it supports a Hilbert space of renormalizable interactions involving arbitrarily high powers of the gravitational fluctuations. These interactions are characterised by being exponentially suppressed for large field amplitude, perturbative in Newton's constant but non-perturbative in Planck's constant. By taking a limit to the boundary of the Hilbert space, diffeomorphism invariance is recovered in the continuum quantum field theory. Thus the so-called conformal factor instability is the key that allows the construction of a genuine continuum limit for quantum gravity.
Speaker: | Prof. Tim Morris (University of Southampton) |
Material: | Slides |
We review scenarios of baryogenesis through leptogenesis at early epochs of the universe, in string-inspired minimal extensions of the Standard Model (SM), involving heavy right-handed Majorana neutrinos. Spontaneous violation of CPT symmetry is induced by appropriate (in general, temperature-dependent) backgrounds of the Kalb-Ramond (KR) axion field, which has its origins in the (bosonic) massless string multiplet. As interesting features of the model, we also discuss two issues associated with quantum (chiral) anomalies: (i) the non-contribution of the KR axion background to the (anomalous) chiral magnetic effect, which arises in the presence of external electromagnetic fields and non-zero chiral chemical potentials of charged fermions and (ii) the potential r\^ole of quantum fluctuations of the KR axion on the (anomalous) radiative generation of a Majorana mass for the right-handed neutrinos themselves.
Speaker: | Prof. Sarben Sarkar (King's College London) |
Material: | Slides |
We consider string theory compactifications where the effective four-dimensional space-time, the internal space and the background fluxes are all time-dependent. For these cases we analyse the existence of four-dimensional effective field theories.
Speaker: | Dr. Tatar Radu (University of Liverpool) |
Material: | Slides |
Conveners: | Prof. Carsten van de Bruck (University of Sheffield) |
Location: | Schuster ( Rutherford Lecture Theatre ) |
TBA
Speaker: | Dr. Florian Kuhnel (Stockholm University) |
Material: | Slides |
Primordial black holes have had a recent surge in popularity due to the LIGO/VIRGO detections and the possibility that they could make up all or part of the dark matter. However, even if you only want to produce one primordial black hole, there are tough requirements for the inflationary potential which can be translated into constraints on the primordial power spectrum. I will show that there is a limit to how fast the power spectrum can grow, and how observational constraints are getting closer and closer to ruling out primordial black holes on certain mass ranges.
Speaker: | Philippa Cole (University of Sussex) |
Material: | Slides |
Primordial Black Holes (PBHs) are appealing candidates for dark matter in the universe but are severely constrained by theoretical and observational constraints. I will focus on the Hawking evaporation limits extended to Kerr Black Holes. These results have been obtained with a new code entitled BlackHawk that I will briefly present. In particular, I will review the isotropic extragalactic gamma ray background constraint and show that the "window" in which PBHs can constitute all of the dark matter depends strongly on the PBH spin. Finally, I will present a way to distinguish Black Holes of primordial origin from PBHs based on the Thorne limit on their spin.
Speaker: | Dr. Alexandre Arbey (Lyon U. and CERN) |
Material: | Slides |
We present a first overview of aSuperIso_DM, a platform based on Mathematica and C++ that is dedicated to the computation of various dark matter observables in the framework of a quantum field theory that can be cast under a Lagrangian form and that features a dark matter particle. aSuperIso_DM generalizes the supersymmetry-specific program SuperIso Relic by relying on an interface to FeynRules to generate a C++ program dedicated to the model under consideration. This C++ code can then be used for calculations of the dark matter relic density and direct and indirect detection cross sections. aSuperIso_DM moreover offers the advantage to allow for alternative cosmological models (which contrasts with other similar public codes), for the visualization of (co-)annihilation Feynman diagrams and for the deriviation of explicit formulae for all relevant squared amplitudes.
Speaker: | Dr. Glenn Robbins (KBFI) |
Material: | Slides |
Conveners: | Jan Kalinowski (University of Warsaw) |
Location: | Schuster ( Bragg Lecture Theatre ) |
In $\mu$-hybrid inflation a nonzero inflaton vacuum expectation value induced by supersymmetry breaking is proportional to the gravitino mass $m_{3/2}$, which can be exploited to resolve the minimal supersymmetric standard model $\mu$ problem. We show how this scenario can be successfully implemented with $m_{3/2} \sim 1-100$~TeV and reheat temperature as low as $10^6$~GeV by employing a minimal renormalizable superpotential coupled with a well defined non-minimal K\"ahler potential. The tensor-to-scalar ratio $r$, a canonical measure of primordial gravity waves in most cases is less than or of the order of $10^{-6}-10^{-3}$.
Speaker: | Ms. Fariha Vardag (Quaid-i-Azam Universtiy, Islamabad, Pakistan) |
Material: | Slides |
We study a class of models in which the Standard Model (SM) is augmented by vector-like leptons:one doublet and a singlet, which are odd under an unbroken discrete Z_2 symmetry. As a result, the neutral component of these additional vector-like leptons are stable and behave as dark matter. We study the phenomenological constraints on the model parameters and elucidate the parameter space for relic density, direct detection and collider signatures of dark matter. In such models, we further add a scalar triplet of hyper charge two and study the consequences. In particular, after electroweak symmetry breaking (EWSB), the triplet scalar gets an induced vacuum expectation value (vev), which yield Majorana masses not only to the light neutrinos but also to vector-like leptonic doublet DM. Due to the Majorana mass of DM, the Z-boson mediated elastic scattering with nucleon is forbidden and hence allowing the model to survive from stringent direct search bound. The DM without scalar triplet lives in a small singlet-doublet leptonic mixing region (sinθ≤0.1) due to large contribution from singlet component and have small mass difference (∆m∼10 GeV) with charged companion, the NLSP (next to lightest stable particle), to aid co-annihilation for yielding correct relic density. Both these observations change to certain extent in presence of scalar triplet to aid observability of hadronically quiet leptonic final states at LHC, while one may also confirm/rule-outthe model through displaced vertex signal of NLSP, a characteristic signature of the model in relic density and direct search allowed parameter space.
Speaker: | Dr. Narendra Sahu (IIT Hyderabad) |
Material: | Slides |
Dynamic relaxation provides an interesting framework which intends to solve the hierarchy problem by postulating, that the observed value of the electroweak scale was determined dynamically in the early Universe. Values of the electroweak scale were scanned during an evolution of axion-like field (a relaxion), with a stopping mechanism responsible for fixing the scale at a small value. The original relaxation proposal depended on an ongoing inflation, putting significant constraints on the inflationary sector. Since then alternative variants of relaxation were proposed, which allow to decouple it from inflation completely. In these scenarios relaxation is stopped though a burst of particle production which happens when the relaxion enters a non-adiabatic region. Qualitative and analytical approach can tell us a lot about the viability of such relaxation models. It is however still interesting to track the relaxation process in detail, which can only be done numerically. In this talk we will present our work towards such analysis done with a goal of investigating a subtle interplay between the relaxion, the electroweak scale, and the produced particles.
Speaker: | Mr. Adam Markiewicz (University of Warsaw) |
Material: | Slides |
Conveners: | Prof. Heinrich Päs (TU Dortmund) |
Location: | Schuster ( Moseley Lecture Theatre ) |
T2K is a long baseline neutrino experiment producing a beam of muon neutrinos at the Japan Particle Accelerator Research Centre on the East coast of Japan and measuring their oscillated state 295 km away at the Super Kamiokande detector. Since 2016 T2K has doubled its data in both neutrino and antineutrino beam modes. Coupled with improvements in analysis techniques this has enabled the experiment to make world leading measurements of the PMNS oscillation parameters \Delta_m^{2}_{32}, sin^2(\theta_{23}) and the CP violating phase \delta_{CP}. In particular the CP conserving values of \delta_{CP} now appear to be disfavoured at the 95\% CL and there are regions of parameter space excluded at the 99.7\% CL. This talk will describe these results and the analysis improvements that have enabled them.
Speaker: | Dr. Laura Lee Kormos (Lancaster University) |
Material: | Slides |
We investigate the performance of T2HK in the presence of a light eV scale sterile neutrino. We study in detail its influence in resolving fundamental issues like mass hierarchy, CP-violation (CPV) induced by the standard CP-phase delta13 and new CP-phase delta14, and the octant ambiguity of theta23. We show for the first time in detail that due to the impressive energy reconstruction capabilities of T2HK, the available spectral information plays an important role to enhance the mass hierarchy discovery reach of this experiment in 3ν framework and also to keep it almost intact even in 4ν scheme. This feature is also of the utmost importance in establishing the CPV due to delta14. As far as the sensitivity to CPV due to delta13 is concerned, it does not change much going from 3ν to 4ν case. We also examine the reconstruction capability of the two phases delta13 and delta14, and find that the typical 1σ uncertainty on delta13 (delta14) in T2HK is ∼ 15^0 (30^0). While determining the octant of theta23, we face a complete loss of sensitivity for unfavorable combinations of unknown delta13 and delta14.
Speaker: | Dr. Sabya Sachi Chatterjee (IPPP, Durham University) |
Material: | Slides |
The MEG experiment took data at the Paul Scherrer Institute in the years 2009-2013 and published the most stringent limit on the charged lepton flavor violating decay mu->egamma: BR(mu->egamma) <4.2 x 10^(-13) @90% C.L. The MEG detector has been upgraded in order to reach a sensitivity of 5 x 10^(-14), which corresponds to an improvement of one order of magnitude. The basic idea of MEG-II is to achieve the highest possible sensitivity by making the maximum use (7 x 10^(7) muons/second) of the available muon intensity at PSI with an improved detector, since MEG ran at a reduced intensity (3 x 10^(7) muons/second) in order to keep the background at a manageable level. The key features of the MEG-II are the increase of the rate capability of all detectors to enable running at the intensity frontier, and to increase the resolutions while maintaining the same detector concept. A new mass, single volume, high granularity tracker, together with a thinner muon stopping target, leads to better spatial, angular and energy positron resolution. A new highly segmented timing counter improves positron timing capabilities. The detector acceptance for positrons is increased by more than a factor 2 by diminishing the material between these two detectors. The liquid Xenon calorimeter has new smaller photosensors (VUV-sensitive SiPM) that replace current phototubes and improve in particular photon energy resolution. The results of the 2018 pre-engineering run, the first with all the sub-detectors, and the current schedule will presented. MEG-II, together with the next generation charged lepton flavor violation experiments Mu3e (mu -> e+e-e+) at PSI and Mu2e and COMET (mu -> e conversion) at Fermilab and JPARK respectively, will reach an unprecedent sensitivity in the next five years. On the same time scale accelerator upgrades are expected that will provide muon beams with intensities of the order of 10^(10)$ muons/second. At this extremely high beam rates, new detector concepts should be adopted in order to overcome the accidental background in mu->egamma searches. Some future directions will be discussed.
Speaker: | Dr. Cecilia Voena (INFN Roma1, on behalf of the MEG Collaboration) |
Material: | Slides |
As the lepton number and lepton flavor are conserved quantities in Standard Model, observation of charged lepton flavor violation (cLFV) process will provide clues on beyond-Standard model theories. COMET is an experiment at J-PARC, Japan, which will search for neutrinoless conversion of muons into electrons in the field of a nucleus (μ− + N → e− + N); a lepton flavor violating process. The experimental sensitivity goal for this process is order of 10^−15 for Phase-I and 10^−17 for Phase-II experiment, which is a factor of 100–10000 improvements correspondingly over existing limits. Recent progresses in facility and detector development will be presented, along with COMET Phase-I and Phase-II experimental schedule.
Speaker: | Prof. Yoshi Uchida (Imperial College London) |
Material: | Slides |
Hawking Points by Prof. Sir Roger Penrose
Location: | Schuster ( Rutherford Lecture Theatre ) |
Material: | poster |
Convener: | Prof. Carlos Wagner (The University of Chicago and Argonne National Laboratory) |
Location: | Rutherford theatre |
Speaker: | Prof. Samaya Nissanke (Amsterdam U.) |
Speaker: | Prof. Cumrun Vafa (Harvard University) |
Material: | Slides |
Convener: | Prof. Alexei Smirnov (Max-Planck Institute for Nuclear Physics, Heidelberg, Germany) |
Location: | Rutherford theatre |
Speaker: | Prof. Manuel Drees (Bonn University) |
Material: | Slides |
Speaker: | Prof. George Efstathiou (Cambridge U.) |