Angular Scaling in Jets

TL;DR

This paper introduces a new jet shape observable based on two-particle angular correlations, which is safe for infrared and collinear divergences, and useful for testing QCD and tuning simulations.

Contribution

It presents a novel angular scaling exponent for jets, providing a new tool for analyzing jet structure and non-perturbative effects in QCD.

Findings

The observable approaches 2 for small resolution parameter R.

It is sensitive to non-perturbative effects at large R.

Useful for testing QCD and tuning Monte Carlo simulations.

Abstract

We introduce a jet shape observable defined for an ensemble of jets in terms of two-particle angular correlations and a resolution parameter R. This quantity is infrared and collinear safe and can be interpreted as a scaling exponent for the angular distribution of mass inside the jet. For small R it is close to the value 2 as a consequence of the approximately scale invariant QCD dynamics. For large R it is sensitive to non-perturbative effects. We describe the use of this correlation function for tests of QCD, for studying underlying event and pile-up effects, and for tuning Monte Carlo event generators.