The effect of neutron skin on inclusive prompt photon production in Pb~+~Pb collisions at the LHC

TL;DR

This paper investigates how neutron skin-thickness in lead nuclei influences inclusive prompt photon production in Pb+Pb collisions at the LHC, highlighting a characteristic enhancement in the central-to-peripheral ratio especially at forward rapidity.

Contribution

It introduces a calculation of the neutron skin effect on prompt photon production and predicts observable enhancements in the central-to-peripheral ratio at LHC energies.

Findings

Neutron skin causes a measurable enhancement in photon production ratios.

The effect is more pronounced at forward rapidity.

Precise measurements are needed to observe this feature experimentally.

Abstract

Recent experiments on lead (\textrm{$Pb_{82}^{208}$}) nuclei have observed the celebrated phenomenon of neutron skin-thickness of low energy nuclear physics. The skin-thickness provides a measure of extension of spatial distribution of neutrons inside the atomic nucleus than protons. We have studied the effect of neutron skin-thickness on inclusive prompt photon production in Pb~+~Pb collisions at the Large Hadron Collider energies. We have calculated the \textquoteleft central-to-peripheral ratio\textquoteright ($R_\textrm{cp}$) of prompt photon production with and without accounting for neutron skin effect. The neutron skin causes a characteristic enhancement in the ratio, in particular at forward rapidity, which is distinguishable in our calculation. However a very precise direct photon measurement up to large transverse momenta would be necessary to constrain the feature in experiment.