Nuclear transverse momentum dependent gluon density at low $x$ and inclusive soft hadron production in proton-lead collisions at LHC

TL;DR

This paper develops a model for gluon density in protons at low x, predicting soft hadron production in proton-lead collisions at the LHC, and shows improved agreement with experimental data.

Contribution

It introduces a nuclear modification of the TMD gluon density within the quark-gluon string model, extending its applicability to pA interactions and low transverse momentum spectra.

Findings

Better description of low-$p_T$ pion and kaon spectra compared to other models.

Predictions consistent with CMS, ATLAS, and ALICE data at 5.02 TeV.

Nuclear modification based on geometrical scaling enhances model accuracy.

Abstract

We report the results of calculations of inclusive soft hadron production in proton-lead collisions at the LHC in the framework of modified quark-gluon string model (QGSM) extended to $pA$ interactions. Our consideration involves the nuclear modification of previously proposed transverse momentum dependent (TMD, or unintegrated) gluon density in a proton, which provides a self-consistent simultaneous description of numerous HERA and LHC data on $pp$, $ep$ and $\gamma p$ processes. Such nuclear modification is based on well established property of geometrical scaling from nucleons to nuclei. Focusing on the region of small $x$ and low scales, we obtain predictions for transverse momentum spectra of pions and kaons at $p_T \leq 1$~GeV. Our results are compared with recent data reported by the CMS, ATLAS and ALICE Collaborations at $\sqrt s = 5.02$~TeV. We find that the developed approach provides a better description of low-$p_T$ data than the predictions made by other groups.