Energy Correlation Functions for Jet Substructure

TL;DR

This paper introduces generalized energy correlation functions as a versatile, subjet-independent tool for analyzing jet substructure, demonstrating their effectiveness in various particle identification tasks through Monte Carlo studies.

Contribution

It presents a novel approach using energy correlation functions to probe jet substructure without explicit subjet identification, enhancing soft and collinear feature analysis.

Findings

2-point correlators effectively discriminate quark and gluon jets

3-point correlators improve boosted W/Z/Higgs boson identification

4-point correlators assist in boosted top quark detection

Abstract

We show how generalized energy correlation functions can be used as a powerful probe of jet substructure. These correlation functions are based on the energies and pair-wise angles of particles within a jet, with (N+1)-point correlators sensitive to N-prong substructure. Unlike many previous jet substructure methods, these correlation functions do not require the explicit identification of subjet regions. In addition, the correlation functions are better probes of certain soft and collinear features that are masked by other methods. We present three Monte Carlo case studies to illustrate the utility of these observables: 2-point correlators for quark/gluon discrimination, 3-point correlators for boosted W/Z/Higgs boson identification, and 4-point correlators for boosted top quark identification. For quark/gluon discrimination, the 2-point correlator is particularly powerful, as can be understood via a next-to-leading logarithmic calculation. For boosted 2-prong resonances the benefit depends on the mass of the resonance.