Pseudorapidity distributions of charged hadrons in lead-lead collisions at sNN=5.36TeV

Abstract

The pseudorapidity (η) distributions of charged hadrons are measured using data collected at the highest ever nucleon-nucleon center-of-mass energy of $\sqrt{s_{{}_{\mathrm{NN}}}}=5.36\text{TeV}$ for collisions of lead-lead ions. The data were recorded by the CMS experiment at the LHC in 2022 and correspond to an integrated luminosity of $0.30\pm 0.03{\mu \text{b}}^{-1}$. Using the CMS silicon pixel detector, the yields of primary charged hadrons produced in the range $\left|\eta \right|<2.6$ are reported. The evolution of the midrapidity particle density as a function of collision centrality is also reported. In the 5% most central collisions, the charged-hadron η density in the range $\left|\eta \right|<0.5$ is found to be $2032\pm 91\text{(syst)}$, with negligible statistical uncertainty. This result is consistent with an extrapolation from nucleus-nucleus collision data at lower center-of-mass energies. Comparisons are made to various Monte Carlo event generators and to previous measurements of lead-lead and xenon-xenon collisions at similar collision energies. These new data detail the dependence of particle production on the collision energy, initial collision geometry, and the size of the colliding nuclei.