Can disoriented chiral condensates form? A dynamical perspective

We address the issue of whether a region of disoriented chiral condensate (DCC), in which the chiral condensate has components along the pion directions, can form. We consider a system going through the chiral phase transition via a quench, in which relaxation of the high temperature phase to the low temperature one occurs rapidly (within a time scale of order ∼1 fm/c). We use a density matrix based formalism that takes both thermal and quantum fluctuations into account nonperturbatively to argue that if the O(4) linear σ model is the correct way to model the situation in QCD, then it is very unlikely, at least in the Hartree approximation, that a large (>10 fm) DCC region will form. Typical sizes of such regions are ∼1–2 fm and the density of pions in such regions is at most of order ∼0.2/${\mathrm{fm}}^3$. We end with some speculations on how large DCC regions may be formed.