Long Range Energy-energy Correlator at the LHC

TL;DR

This paper investigates azimuthal correlations in proton-proton collisions at the LHC, revealing how gluon spin structures influence angular asymmetries and potentially explaining the near-side ridge phenomenon in high-multiplicity events.

Contribution

It introduces a novel application of the nucleon energy-energy correlator framework to predict azimuthal asymmetries based on gluon helicity, with a unique power counting rule for different jet multiplicities.

Findings

os(2\,)symmetry starts at (^2) for dijet

os(2\,)symmetry starts at () for three jet

os(2\,)symmetry is (1) for four or more jets

Abstract

We study the forward-backward azimuthal angular correlations of hadrons in association with multi-particle production in the central rapidity region in proton-proton collisions at the LHC. We apply the nucleon energy-energy correlator framework, where the spinning gluon distribution introduces a nontrivial $\cos(2\phi)$ asymmetries. We will demonstrate that the fundamental helicity structure of QCD amplitudes predicts a unique power counting rule: $\cos(2\phi)$ asymmetry starts at ${O}(\alpha_s^2)$ order for dijet, ${O}(\alpha_s)$ for three jet and ${O}(1)$ for four (and more) jet productions. Our results will help us to understand the long standing puzzle of nearside ridge behavior observed in high multiplicity events of $pp$ collisions at the LHC.