Quenching through the QCD chiral phase transition

Abstract

We present a detailed numerical and analytical study of the out-of-equilibrium dynamics of Model G, the dynamical universality class relevant to the chiral phase transition. We perform numerical 3D stochastic (Langevin) simulations of the $O(4)$ critical point for large lattices in the chiral limit. We quench the system from the high-temperature unbroken phase to the broken phase and study the non-equilibrium dynamics of pion fields. Strikingly, the non-equilibrium evolution of the two-point functions exhibits a regime of growth, a parametrically large enhancement, and a subsequent slow relaxation to equilibrium. We analyze our numerical results using dynamic critical scaling and mean-field theory. The growth of the two point functions is determined by the non-linear dynamics of an ideal non-abelian superfluid, which is a limit of Model G that reflects the broken chiral symmetry. We also relate the non-equilibrium two-point functions to a long-lived parametric enhancement of soft pion yields relative to thermal equilibrium following a quench.

45 pages, 11 figures; added quasi-particle description of pion waves; published version, see companion letter "Supercooled Goldstone Bosons at the QCD Chiral Phase Transition" arXiv:2504.03514

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Cited by in corpus (1)

• Supercooled Goldstone Bosons at the QCD Chiral Phase Transition