Investigating the Topology Dependence of Quark and Gluon Jets

TL;DR

This paper studies how the environment or topology affects the ability to distinguish quark-initiated jets from gluon-initiated jets at the LHC, highlighting challenges in calibration and the importance of jet substructure observables.

Contribution

It provides an analysis of the topology dependence of quark and gluon jets in simulation, identifying key phase space regions and observables for future comparative studies.

Findings

Topology significantly influences jet radiation patterns.

Certain jet substructure observables are sensitive to environment effects.

Framework established for comparing generators and data.

Abstract

As most target final states for searches and measurements at the Large Hadron Collider have a particular quark/gluon composition, tools for distinguishing quark- from gluon-initiated jets can be very powerful. In addition to the difficulty of the classification task, quark-versus-gluon jet tagging is challenging to calibrate. The difficulty arises from the topology dependence of quark-versus-gluon jet tagging: since quarks and gluons have net quantum chromodynamic color charge while only colorless hadrons are measured, the radiation pattern inside a jet of a particular type depends on the rest of its environment. Given a definition of a quark or gluon jet, this paper studies the topology dependence of such jets in simulation. A set of phase space regions and jet substructure observables are identified for further comparative studies between generators and eventually in data.