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Systematic quark/gluon identification with ratios of likelihoods

Bright-Thonney, Samuel ; Moult, Ian ; Nachman, Benjamin and Prestel, Stefan LU (2022) In Journal of High Energy Physics 2022(12).
Abstract

Discriminating between quark- and gluon-initiated jets has long been a central focus of jet substructure, leading to the introduction of numerous observables and calculations to high perturbative accuracy. At the same time, there have been many attempts to fully exploit the jet radiation pattern using tools from statistics and machine learning. We propose a new approach that combines a deep analytic understanding of jet substructure with the optimality promised by machine learning and statistics. After specifying an approximation to the full emission phase space, we show how to construct the optimal observable for a given classification task. This procedure is demonstrated for the case of quark and gluons jets, where we show how to... (More)

Discriminating between quark- and gluon-initiated jets has long been a central focus of jet substructure, leading to the introduction of numerous observables and calculations to high perturbative accuracy. At the same time, there have been many attempts to fully exploit the jet radiation pattern using tools from statistics and machine learning. We propose a new approach that combines a deep analytic understanding of jet substructure with the optimality promised by machine learning and statistics. After specifying an approximation to the full emission phase space, we show how to construct the optimal observable for a given classification task. This procedure is demonstrated for the case of quark and gluons jets, where we show how to systematically capture sub-eikonal corrections in the splitting functions, and prove that linear combinations of weighted multiplicity is the optimal observable. In addition to providing a new and powerful framework for systematically improving jet substructure observables, we demonstrate the performance of several quark versus gluon jet tagging observables in parton-level Monte Carlo simulations, and find that they perform at or near the level of a deep neural network classifier. Combined with the rapid recent progress in the development of higher order parton showers, we believe that our approach provides a basis for systematically exploiting subleading effects in jet substructure analyses at the Large Hadron Collider (LHC) and beyond.

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Please use this url to cite or link to this publication:
author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Jets and Jet Substructure, Parton Shower
in
Journal of High Energy Physics
volume
2022
issue
12
article number
21
publisher
Springer
external identifiers
  • scopus:85143643681
ISSN
1029-8479
DOI
10.1007/JHEP12(2022)021
language
English
LU publication?
yes
id
d2e064b3-bf50-4856-be7a-0fcd9370de46
date added to LUP
2022-12-22 12:42:50
date last changed
2024-04-14 23:52:00
@article{d2e064b3-bf50-4856-be7a-0fcd9370de46,
  abstract     = {{<p>Discriminating between quark- and gluon-initiated jets has long been a central focus of jet substructure, leading to the introduction of numerous observables and calculations to high perturbative accuracy. At the same time, there have been many attempts to fully exploit the jet radiation pattern using tools from statistics and machine learning. We propose a new approach that combines a deep analytic understanding of jet substructure with the optimality promised by machine learning and statistics. After specifying an approximation to the full emission phase space, we show how to construct the optimal observable for a given classification task. This procedure is demonstrated for the case of quark and gluons jets, where we show how to systematically capture sub-eikonal corrections in the splitting functions, and prove that linear combinations of weighted multiplicity is the optimal observable. In addition to providing a new and powerful framework for systematically improving jet substructure observables, we demonstrate the performance of several quark versus gluon jet tagging observables in parton-level Monte Carlo simulations, and find that they perform at or near the level of a deep neural network classifier. Combined with the rapid recent progress in the development of higher order parton showers, we believe that our approach provides a basis for systematically exploiting subleading effects in jet substructure analyses at the Large Hadron Collider (LHC) and beyond.</p>}},
  author       = {{Bright-Thonney, Samuel and Moult, Ian and Nachman, Benjamin and Prestel, Stefan}},
  issn         = {{1029-8479}},
  keywords     = {{Jets and Jet Substructure; Parton Shower}},
  language     = {{eng}},
  number       = {{12}},
  publisher    = {{Springer}},
  series       = {{Journal of High Energy Physics}},
  title        = {{Systematic quark/gluon identification with ratios of likelihoods}},
  url          = {{http://dx.doi.org/10.1007/JHEP12(2022)021}},
  doi          = {{10.1007/JHEP12(2022)021}},
  volume       = {{2022}},
  year         = {{2022}},
}