Photon multiplicity measurements at forward rapidity in the ALICE experiment at CERN

Abstract

We present the first preliminary results on photon multiplicity measurements at LHC at forward pseudorapidity (2.3 $\textless$ $\eta$ $\textless$ 3.9) in proton-proton ($pp$) collisions at $\sqrt{s}$ = 7 TeV. The multiplicity distribution is found to be reasonably well explained by a double Negative Binomial Distribution (NBD). The average photon multiplicity increases logarithmically with $\sqrt{s}$. It is found that none of the models we used (PYTHIA6D6T, PHOJET, and HERWIG) could explain the data.