Pseudorapidity distributions of charged hadrons in proton-lead collisions at $\sqrt{s_{_\mathrm{NN}}} =$ 5.02 and 8.16 TeV

TL;DR

This paper reports measurements of charged hadron pseudorapidity distributions in proton-lead collisions at 5.02 and 8.16 TeV, comparing results with theoretical models and other collision systems to understand particle production mechanisms.

Contribution

It provides the first detailed measurements of charged hadron distributions in proton-lead collisions at these energies, offering new data for testing theoretical models and understanding nuclear effects.

Findings

Charged-hadron multiplicity densities increase with collision energy.

Data generally agree with some theoretical predictions and Monte Carlo models.

Comparison with other collision systems highlights nuclear effects on particle production.

Abstract

The pseudorapidity distributions of charged hadrons in proton-lead collisions at nucleon-nucleon center-of-mass energies $\sqrt{s_{_\mathrm{NN}}} =$ 5.02 and 8.16 TeV are presented. The measurements are based on data samples collected by the CMS experiment at the LHC. The number of primary charged hadrons produced in non-single-diffractive proton-lead collisions is determined in the pseudorapidity range $|\eta_\mathrm{lab}| <$ 2.4. The charged-hadron multiplicity distributions are compared to the predictions from theoretical calculations and Monte Carlo event generators. In the center-of-mass pseudorapidity range $|\eta_\mathrm{cm}| < 0.5$, the average charged-hadron multiplicity densities $<\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta_{\mathrm{cm}}>$$\vert_{|\eta_{\mathrm{cm}}| < 0.5}$ are 17.31 $\pm$ 0.01 (stat) $\pm$ 0.59 (syst) and 20.10 $\pm$ 0.01 (stat) $\pm$ 0.85 (syst) at $\sqrt{s_{_\mathrm{NN}}} =$ 5.02 and 8.16 TeV, respectively. The particle densities per participant nucleon are compared to similar measurements in proton-proton, proton-nucleus, and nucleus-nucleus collisions.