We compute initial conditions in heavy ion collisions within the color glass condensate framework by combining the impact parameter dependent saturation model with the classical Yang-Mills description of initial Glasma fields. In addition to fluctuations of nucleon positions, this impact parameter dependent Glasma description includes quantum fluctuations of color charges on the length scale determined by the inverse nuclear saturation scale $Q_s$. The model naturally produces initial energy fluctuations that are described by a negative binomial distribution. The ratio of triangularity to eccentricity ${\epsilon }_3/{\epsilon }_2$ is close to that in a model tuned to reproduce experimental flow data. We compare transverse momentum spectra and $v_{2,3,4}(p_T)$ of pions from different models of initial conditions using relativistic viscous hydrodynamic evolution.

• Received 7 March 2012

DOI:https://doi.org/10.1103/PhysRevLett.108.252301