Dynamical Evolution of the Scalar Condensate in Heavy Ion Collisions

Abstract

We derive the effective coarse-grained field equation for the scalar condensate of the linear sigma model in a simple and straightforward manner using linear response theory. The dissipative coefficient is calculated at tree level on the basis of the physical processes of sigma-meson decay and of thermal sigma-mesons and pions knocking sigma-mesons out of the condensate. The field equation is solved for hot matter undergoing either one or three dimensional expansion and cooling in the aftermath of a high energy nuclear collision. The results show that the time constant for returning the scalar condensate to thermal equilibrium is of order 2 fm/c.

Comments: 19 pages, 3 figures are embedded at the end. The effect of the time dependence of the condensate v is included in this revised version. Numerical work is redone accordingly