Measurement of the Inelastic Proton-Proton Cross Section at sqrt(s) = 13 TeV with the ATLAS Detector at the LHC

This Letter presents a measurement of the inelastic proton-proton cross section using 60 μb−1 of pp collisions at a center-of-mass energy sqrt(s) of 13 TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using highly efficient plastic scintillators in the forward region of the detector. A cross section of 68.2±1.5 mb is measured in the fiducial region ξ=M2X/s>10−6, where MX is the largest invariant mass of the two hadronic systems separated by the largest rapidity gap in the event. For diffractive events this corresponds to cases where at least one proton dissociates to a system of mass larger than 13 GeV. The measurement agrees with a range of theoretical predictions. When extrapolated to the full phase space, the result is consistent with an inelastic cross section increasing with center-of-mass energy, as observed at lower energies.