Pure Samples of Quark and Gluon Jets at the LHC

TL;DR

This paper explores methods to obtain high-purity samples of quark and gluon jets at the LHC using simple kinematic cuts, enabling better studies of jet properties for physics research.

Contribution

It demonstrates how specific multijet and jets+X samples at the 7 TeV LHC can achieve high purity of quark and gluon jets with reasonable cross sections.

Findings

pp → γ+2jets yields 98% pure quark jets at 200 GeV with 5 pb cross section

pp → 3jets can produce 10 pb of jets with 90% gluon purity at 200 GeV

b+2jets sample useful for gluons if b-tagging is highly efficient

Abstract

Having pure samples of quark and gluon jets would greatly facilitate the study of jet properties and substructure, with many potential standard model and new physics applications. To this end, we consider multijet and jets+X samples, to determine the purity that can be achieved by simple kinematic cuts leaving reasonable production cross sections. We find, for example, that at the 7 TeV LHC, the pp {\to} {\gamma}+2jets sample can provide 98% pure quark jets with 200 GeV of transverse momentum and a cross section of 5 pb. To get 10 pb of 200 GeV jets with 90% gluon purity, the pp {\to} 3jets sample can be used. b+2jets is also useful for gluons, but only if the b-tagging is very efficient.