Measurement of the energy density as a function of pseudorapidity in proton-proton collisions at $\sqrt{s}=$ 13 TeV

Abstract

A measurement of the energy density in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=$ 13 TeV is presented. The data have been recorded with the CMS experiment at the LHC during low luminosity operations in 2015. The energy density is studied as a function of pseudorapidity in the ranges $-$6.6 $<\eta$ $<-$5.2 and 3.15 $<|\eta |<$ 5.20. The results are compared with the predictions of several models. All the models considered suggest a different shape of the pseudorapidity dependence compared to that observed in the data. A comparison with LHC proton-proton collision data at $\sqrt{s}=$ 0.9 and 7 TeV confirms the compatibility of the data with the hypothesis of limiting fragmentation.

Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/FSQ-15-006 (CMS Public Pages)