Pressure Anisotropy in Heavy Ion Collisions from Color Glass Condensate
  We generalize calculations of the energy-momentum tensor for classical gluon fields in the McLerran-Venugopalan model using the small-$\tau$ power series expansion method. Results to all orders for the energy density and pressures are given in the leading $Q^2$ approximation and with the inclusion of running coupling effects. The energy density and transverse pressure decrease monotonically with time while the longitudinal pressure starts from a negative value and increases towards zero. 
Ming Li and Joseph I. Kapusta
nucl-th