Pseudorapidity density of charged particles in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

TL;DR

This paper reports the measurement of charged-particle pseudorapidity density in p-Pb collisions at 5.02 TeV, providing new data to constrain models of particle production in high-energy nuclear collisions.

Contribution

It presents the first detailed measurement of pseudorapidity density in p-Pb collisions at this energy, offering new experimental constraints.

Findings

Average midrapidity density is 16.81 with 0.71 syst.

Density is 16% lower than in NSD pp collisions at the same energy.

Density is 84% higher than in d-Au collisions at 0.2 TeV.

Abstract

The charged-particle pseudorapidity density measured over 4 units of pseudorapidity in non-single-diffractive (NSD) p-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 5.02$ TeV is presented. The average value at midrapidity is measured to be $16.81 \pm 0.71$ (syst.), which corresponds to $2.14 \pm 0.17$ (syst.) per participating nucleon. This is 16% lower than in NSD pp collisions interpolated to the same collision energy, and 84% higher than in d-Au collisions at $\sqrt{s_{\rm NN}} = 0.2$ TeV. The measured pseudorapidity density in p-Pb collisions is compared to model predictions, and provides new constraints on the description of particle production in high-energy nuclear collisions.