Manchester Particle Physics Seminars, Colloquia and Meetings

Frederic Dreyer: The Lund Jet Plane

Friday, 16 November 2018 from to (Europe/London)
at Schuster ( 54-6-6.40 - Niels Bohr Common Room )
Description
Lund diagrams, a theoretical representation of the phase space within jets, have long been used in discussing parton showers and resummations. I will show that they can be created for individual jets through repeated Cambridge/Aachen declustering, providing a powerful visual representation of the radiation within any given jet. Concentrating on the primary Lund plane, I will outline some of its analytical properties, highlight its scope for constraining Monte Carlo simulations and comment on its relation with existing observables. I will then examine its use for boosted electroweak boson tagging at high momenta. It provides good performance when used as an input to machine learning. Much of this performance can be reproduced also within a transparent log-likelihood method, whose underlying assumption is that different regions of the primary Lund plane are largely decorrelated. This suggests a potential for unique insight and experimental validation of the features being used by machine-learning approaches.