Abstract
The pseudorapidity distribution of charged hadrons in $pp$ collisions at $\sqrt{s} =13 TeV$ is measured using a data sample obtained with the CMS detector, operated at zero magnetic field, at the CERN LHC. The yield of primary charged long-lived hadrons produced in inelastic $pp$ collisions is determined in the central region of the CMS pixel detector $(\eta <2)$ using both hit pairs and reconstructed tracks. For central pseudorapidities (abs(eta) < 0.5), the charged-hadron multiplicity density is dN/d(eta)[charged,abs(eta) < 0.5] = 5.49 +/- 0.01 (stat) +/- 0.17 (sys), a value obtained by combining the two methods. The result is compared to predictions from Monte Carlo event generators and to similar measurements made at lower collision energies.
CMS Collaboration