1206.6805 (Bjoern Schenke et al.)

Event-by-event gluon multiplicity, energy density and eccentricities at
RHIC and LHC    [PDF]

Bjoern Schenke, Prithwish Tribedy, Raju Venugopalan

The event-by-event multiplicity distribution, the energy densities and energy density weighted eccentricity moments epsilon_n (up to n=6) at early times in heavy-ion collisions at both RHIC (root-s=200 GeV) and LHC (root-s=2.76 TeV) are computed in the IP-Glasma model. This framework combines the impact parameter dependent saturation model (IP-Sat) for nucleon parton distributions (constrained by HERA deeply inelastic scattering data) with an event-by-event classical Yang-Mills description of early-time gluon fields in heavy-ion collisions. The model produces multiplicity distributions that are convolutions of negative binomial distributions without further assumptions or parameters. The eccentricity moments are compared to the MC-KLN model; a noteworthy feature is that fluctuation dominated odd moments are consistently larger than in the MC-KLN model.

View original: http://arxiv.org/abs/1206.6805