Hadron Multiplicity in Pb+Pb Collisions at √s=2.76 TeV from Color Glass Condensate

The pseudo-rapidity distribution of charged hadron multiplicity in Pb+Pb collisions at √s=2.76 TeV is studied by using Color Glass Condensate dynamics in the fixed coupling case. We fit the HERA experimental data with heavy parton mass effect to obtain saturation exponent λ=0.22. It is found that the charged hadron multiplicity can only describe after including heavy parton mass effect due to a large amount of heavy partons produced at large hadron collider (LHC) energy. The pomeron loop effect contribution to hadron production is also investigated. It shows that charged hadron multiplicity is underestimated by including the pomeron loop effect, which indicates that the pomeron loop effect may not exist at LHC energy.