The properties of quark and gluon jets, and the differences between them, are increasingly important at the LHC. However, Monte Carlo event generators are normally tuned to data from e+e− collisions which are primarily sensitive to quark-initiated jets. In order to improve the description of gluon jets we make improvements to the perturbative and the non-perturbative modelling of gluon jets...
We calculate quark and gluon jet fraction in multi-jet final states at the LHC, which is based on perturbative QCD at next-to-double logarithmic accuracy. We find a measurable scaling pattern of the fraction. This is related to a performance of new physics searches using quark-gluon jet discrimination in multi-jet final states, and would be useful for more understanding of QCD and tuning of...
Neural network-based algorithms provide a promising approach to jet classification problems, such as boosted top jet tagging. In this talk, I will discuss that the jet observable defined by the convolutional neural network obeys the canonical definition of infrared safety: it is unaffected by the presence of the extra gluon, as long as it is soft or collinear with one of the quarks, which...
Jet grooming has an important significance in the study of QCD event shapes. Soft drop grooming is a great tool for reducing the soft contamination to the jet, while at the same time allowing one to calculate groomed event shape cross sections in perturbation theory. It also results in reduced corrections to the perturbative cross section from hadronization and underlying event. However,...
The pull angle was introduced as a sensitive probe of the color flow between jets and has been measured in W boson decays by ATLAS. Despite being infrared and collinear unsafe, it can be calculated in resummed perturbation theory. In this talk, I will review the pull angle, introduce our calculation, and compare it to ATLAS data.
We carry out first analytical calculations for top taggers along similar lines to those already performed for the most common W/Z/H taggers. We discuss both the CMS top tagger as well as the Y-splitter method adapted for top tagging. A novel feature of our calculations is the use of triple-collinear splitting functions to describe 1 \to 3 decays. We find that the default CMS tagger is infrared...
We present an evolution algorithm for soft gluon exchanges and the resummation of non-global logarithms. Our approach applies to generic hard-scattering processes involving any number of coloured partons and we present a reformulation of the algorithm in such a way as to make the cancellation of infrared divergences explicit. Handling large colour matrices presents the most significant...
