Measurement of the Inelastic Cross Section in Proton-Lead Collisions at a Centre-of-Mass Energy per Nucleon Pair of 5.02 TeV

CMS [UCL] Basegmez, Suzan [UCL] Beluffi, Camille [UCL] Bondu, Olivier [UCL] Brochet, Sébastien [UCL] Bruno, Giacomo [UCL] Castello, Roberto [UCL] Caudron, Adrien [UCL] Ceard, Ludivine [UCL] Da Silveira, Gustavo Gil [UCL] Delaere, Christophe [UCL] Favart, Denis [UCL] Forthomme, Laurent [UCL] Giammanco, Andrea [UCL] Hollar, Jonathan [UCL] Jafari, Abideh [UCL] Jez, Pavel [UCL] Komm, Matthias [UCL] Lemaitre, Vincent [UCL] Mertens, Alexandre [UCL] Nuttens, Claude [UCL] Perrini, Lucia [UCL] Pin, Arnaud [UCL] Piotrzkowski, Krzysztof [UCL] Popov, Andrey [UCL] Quertenmont, Loic [UCL] Selvaggi, Michele [UCL] Vidal Maroño, Miguel [UCL] et al.

The inelastic hadronic cross section in proton-lead collisions at a centre-of-mass energy pernucleon pair of 5.02 TeV is measured with the CMS detector at the LHC. The data sample,corresponding to an integrated luminosity of $ mathcal{L} =12.6 pm 0.4, mathrm{nb}^{-1}$, has been collected with an unbiased trigger for inclusive particle production. The cross section is obtained from the measured number of proton-lead collisions with hadronic activity produced in the pseudo rapidity $ eta $ ranges between 3 and 5 and/or $ -5 $ and $ -3 $, corrected for photon-induced contributions, experimental acceptance,and other instrumental effects. The inelastic cross section is measured to be $sigma_{ ext{inel}} ( ext{pPb}) = 2061 pm 3, (mathrm{stat}) pm 34, (mathrm{syst}) pm 72, (mathrm{lumi}), mathrm{mb}$. Various Monte Carlo generators, commonly used in heavy ion and cosmic ray physics, are found to reproduce the data within uncertainties. The value of $ sigma_{ ext{inel}} ( ext{pPb}) $ is compatible with that expected from the proton-proton cross section at 5.02 TeV scaled up within a simple Glauber approach to account for multiple scatterings in the lead nucleus, indicating that further net nuclear corrections are small.