Probing Quarkonium Production Mechanisms with Jet Substructure

TL;DR

This paper investigates quarkonium production mechanisms using jet substructure analysis with fragmenting jet functions, providing a method to distinguish different NRQCD channels based on their energy dependence.

Contribution

It introduces a novel approach using FJFs to differentiate quarkonium production channels and predicts their distinct energy behaviors at fixed momentum fractions.

Findings

Gluon FJF decreases with energy if 1S_0^(8) dominates

Different production channels show distinct behaviors as a function of jet energy

Method enables discrimination of NRQCD production mechanisms

Abstract

We use fragmenting jet functions (FJFs) in the context of quarkonia to study the production channels predicted by NRQCD (3S_1^(1), 3S_1^(8), 1S_0^(8), 3P_J^(8)). We choose a set of FJFs that give the probability to find a quarkonium with a given momentum fraction inside a cone-algorithm jet with fixed cone size and energy. This observable gives several lever arms that allow one to distinguish different production channels. In particular, we show that at fixed momentum fraction the individual production mechanisms have distinct behaviors as a function of the the jet energy. As a consequence of this fact, we arrive at the robust prediction that if the depolarizing 1S_0^(8) matrix element dominates, then the gluon FJF will diminish with increasing energy for fixed momentum fraction, z, and z > 0.5.