Utilizing the Langevin equation for the linear σ model we investigate the interplay of friction and white noise on the evolution and stability of collective pionic fields in energetic heavy ion collisions. We find that the smaller the volume, the more stable transverse (pionic) fluctuations become on a homogeneous disoriented chiral field background (the average transverse mass ⟨m2t increases). On the other hand the variance of m2t ⟩ increases even more, so for a system thermalized in an initial volume of 10fm3 about 96% and even in 1000 fm3 about 60% of the individual trajectories enter into unstable regions (m2t < 0) for a while during a rapid one-dimensional expansion (τ0 = 1 fm/c). In contrast the ensemble averaged solution in this case remains stable. This result supports the idea of looking for disoriented chiral condensate (DCC) formation in individual events.
ASJC Scopus subject areas
- Physics and Astronomy(all)