Measurement of the inelastic pPb cross section at 5.02 TeV

A measurement of the inelastic proton-lead (pPb) cross section at a nucleon-nucleon centre-of-mass energy of $5.02\,$TeV is presented using the CMS detector at the LHC. Inelastic collisions are tagged using the forward calorimeters at pseudorapidities $3<|\eta|<5$. Two different event selections are used: (i) a coincidence of both sides of the detector, and (ii) a single-sided event selection. These two selections have different sensitivity to contributions from photon induced ($\gamma$p) collisions and hadronic diffractive interactions. The value of the hadronic inelastic cross section is measured within the CMS acceptance and extrapolated to its total value. The photon-induced contribution is subtracted. The final result is $\sigma_{\text{inel}}=2.06\pm0.08\,$b. The uncertainty is dominated by the luminosity determination. This measurement of the inelastic cross section is consistent with the expectation from the Glauber approach.