Energy Correlators Taking Charge

TL;DR

This paper develops a formalism to analyze energy correlations between hadrons with different quantum numbers in jets, revealing new insights into the confinement transition in QCD through universal non-perturbative functions called joint track functions.

Contribution

It introduces joint track functions to compute energy correlations between hadrons with various quantum numbers, extending jet substructure analysis into the non-perturbative regime.

Findings

Enhanced small angle correlations between opposite-sign hadrons.

Scaling behavior of C-odd three-point functions.

Systematic computation of new jet substructure observables.

Abstract

The confining transition from asymptotically free partons to hadrons remains one of the most mysterious aspects of Quantum Chromodynamics. With the wealth of high quality jet substructure data we can hope to gain new experimental insights into the details of its dynamics. Jet substructure has traditionally focused on correlations, $\langle \mathcal{E}(n_1) \mathcal{E}(n_2) \cdots \mathcal{E}(n_k) \rangle$, in the energy flux of hadrons. However, significantly more information about the confinement transition is encoded in how energy is correlated between hadrons with different quantum numbers, for example electric charge. In this Letter we develop the field theoretic formalism to compute general correlations, $\langle \mathcal{E}_{R_1}(n_1) \mathcal{E}_{R_2}(n_2) \cdots\mathcal{E}_{R_k}(n_k) \rangle$, between the energy flux carried by hadrons with quantum numbers $R_i$, by introducing new universal non-perturbative functions, which we term joint track functions. Using this formalism we show that the strong interactions introduce enhanced small angle correlations between opposite-sign hadrons, relative to like-sign hadrons, identifiable as an enhanced scaling of $\langle \mathcal{E}_+(n_1) \mathcal{E}_-(n_2) \rangle$ relative to $\langle \mathcal{E}_+(n_1) \mathcal{E}_+(n_2) \rangle$. We are also able to compute the scaling of a $C$-odd three-point function, $\langle \mathcal{E}_\mathcal{Q}(n_1) \mathcal{E}_\mathcal{Q}(n_2) \mathcal{E}_\mathcal{Q}(n_3) \rangle$. Our results greatly extend the class of systematically computable jet substructure observables, pushing perturbation theory deeper into the parton to hadron transition, and providing new observables to understand the dynamics of confinement.