Hao-Yu Liu, Xiaohui Liu, Ji-Chen Pan, Feng Yuan, and Hua Xing Zhu, Nucleon Energy Correlators for the Color Glass Condensate, Phys. Rev. Lett. 130, 181901 (2023)
Small-x gluon saturation has been one of the central focuses in the nuclear physics community in recent years and will be a major research area in the future Electron Ion Collider. We demonstrate the recently proposed nucleon energy-energy correlator (NEEC) fEEC(x,θ) 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 θ distribution. We find that the saturation prediction is significantly different from the expectation of the collinear factorization.
Figure: The xB and Q2 measurement in DIS with a forward detector that records the energy flow ∑iEi at the angle θ. The leading contribution is also illustrated where the collinear splitting initiates the DIS process and a daughter parton that hits the detector at θ ≪ 1. The momentum fractions are shown.
See also: Synopsis from APS Physics, DOE Highlight
Illuminating nucleon-gluon interference via calorimetric asymmetry, Xiao Lin Li, Xiaohui Liu, Feng Yuan, and Hua Xing Zhu, Phys. Rev. D 108, L091502
