Nucleon Energy Correlators for the Color Glass Condensate

TL;DR

This paper introduces the nucleon energy-energy correlator as a new inclusive probe for gluon saturation in small-$x$ regimes during $eA$ collisions, revealing significant differences from collinear factorization predictions.

Contribution

It proposes the nucleon EEC as a novel, fully inclusive observable to study gluon saturation effects at small-$x$, without requiring jet or hadron detection.

Findings

Nucleon EEC can effectively reveal gluon saturation.

Saturation effects significantly alter the shape of the $ heta$-distribution.

The predictions differ notably from collinear factorization expectations.

Abstract

We demonstrate the recently proposed nucleon energy-energy correlator (nucleon EEC) $f_{\rm EEC}(x,\theta)$ can unveil the gluon saturation in the small-$x$ regime in $eA$ collisions. The novelty of this probe is that it is fully inclusive just like the deep-inelastic scattering (DIS), with no requirements of jets or hadrons, but still provides an evident portal to the small-$x$ dynamics through the shape of the $\theta$-distribution. We find that the saturation prediction is significantly different from the expectation of the collinear factorization.