Quantifying the performance of jet definitions for kinematic reconstruction at the LHC

Matteo Cacciari, Juan Rojo, Gavin P. Salam, Gregory Soyez

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

We present a strategy to quantify the performance of jet definitions in kinematic reconstruction tasks. It is designed to make use exclusively of physical observables, in contrast to previous techniques which often used unphysical Monte Carlo partons as a reference. It is furthermore independent of the detailed shape of the kinematic distributions. We analyse the performance of 5 jet algorithms over a broad range of jet-radii, for sources of quark jets and gluon jets, spanning the energy scales of interest at the LHC, both with and without pileup. The results allow one to identify optimal jet definitions for the various scenarios. They confirm that the use of a small jet radius (R\simeq 0.5) for quark-induced jets at moderate energy scales, O(100 GeV), is a good choice. However, for gluon jets and in general for TeV scales, there are significant benefits to be had from using larger radii, up to R\gtrsim 1. This has implications for the span of jet-definitions that the LHC experiments should provide as defaults for searches and other physics analyses.
Original languageEnglish
JournalJournal of High Energy Physics
Volume2008
Issue number12
DOIs
Publication statusPublished - 7 Oct 2008

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kinematics
radii
quarks
partons
physics
energy

Bibliographical note

24 pages, 9 figures, with c. 100000 supplementary plots available online at http://quality.fastjet.fr/

Keywords

  • hep-ph

Cite this

Cacciari, Matteo ; Rojo, Juan ; Salam, Gavin P. ; Soyez, Gregory. / Quantifying the performance of jet definitions for kinematic reconstruction at the LHC. In: Journal of High Energy Physics. 2008 ; Vol. 2008, No. 12.
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abstract = "We present a strategy to quantify the performance of jet definitions in kinematic reconstruction tasks. It is designed to make use exclusively of physical observables, in contrast to previous techniques which often used unphysical Monte Carlo partons as a reference. It is furthermore independent of the detailed shape of the kinematic distributions. We analyse the performance of 5 jet algorithms over a broad range of jet-radii, for sources of quark jets and gluon jets, spanning the energy scales of interest at the LHC, both with and without pileup. The results allow one to identify optimal jet definitions for the various scenarios. They confirm that the use of a small jet radius (R\simeq 0.5) for quark-induced jets at moderate energy scales, O(100 GeV), is a good choice. However, for gluon jets and in general for TeV scales, there are significant benefits to be had from using larger radii, up to R\gtrsim 1. This has implications for the span of jet-definitions that the LHC experiments should provide as defaults for searches and other physics analyses.",
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Quantifying the performance of jet definitions for kinematic reconstruction at the LHC. / Cacciari, Matteo; Rojo, Juan; Salam, Gavin P.; Soyez, Gregory.

In: Journal of High Energy Physics, Vol. 2008, No. 12, 07.10.2008.

Research output: Contribution to JournalArticleAcademicpeer-review

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AU - Salam, Gavin P.

AU - Soyez, Gregory

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AB - We present a strategy to quantify the performance of jet definitions in kinematic reconstruction tasks. It is designed to make use exclusively of physical observables, in contrast to previous techniques which often used unphysical Monte Carlo partons as a reference. It is furthermore independent of the detailed shape of the kinematic distributions. We analyse the performance of 5 jet algorithms over a broad range of jet-radii, for sources of quark jets and gluon jets, spanning the energy scales of interest at the LHC, both with and without pileup. The results allow one to identify optimal jet definitions for the various scenarios. They confirm that the use of a small jet radius (R\simeq 0.5) for quark-induced jets at moderate energy scales, O(100 GeV), is a good choice. However, for gluon jets and in general for TeV scales, there are significant benefits to be had from using larger radii, up to R\gtrsim 1. This has implications for the span of jet-definitions that the LHC experiments should provide as defaults for searches and other physics analyses.

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