Dihadron fragmentation framework for near-side energy-energy correlators

TL;DR

This paper introduces a dihadron fragmentation function framework for analyzing near-side energy-energy correlators across different regions, establishing a connection between nonperturbative and perturbative descriptions and fitting experimental data.

Contribution

It proposes the EEC-DiFF function to unify analysis of free hadron, transition, and quark/gluon regions in near-side EECs, enabling simultaneous theoretical treatment.

Findings

First fit of dihadron framework to experimental data

Reasonable agreement with measurements in free hadron and transition regions

Reproduction of key features of near-side EECs

Abstract

We establish an approach to analyze the free hadron and transition (nonperturbative) regions of near-side energy-energy correlators (EECs) based on dihadron fragmentation functions (DiFFs). We introduce a (nonperturbative) function we call the "EEC-DiFF" and explicitly show that expanding it for large relative transverse momentum between the two hadrons gives the $O(\alpha_s)$ expression for the "EEC jet" function used in the quark/gluon (perturbative) region. This connection indicates that a formal theoretical matching will be able to bridge the free hadron, transition, and quark/gluon regions and allow all of them to be analyzed simultaneously. We further derive a result valid for near-side EECs in the free hadron and transition regions of $e^+e^-$ annihilation in terms of the EEC-DiFF. Using a simple model for the function, we perform the first fit within the dihadron framework to experimental data in this regime. We find reasonable agreement with the measurements and reproduce the salient features of near-side EECs in the free hadron and transition regions.