How spinodal decomposition influences observables at FAIR energies

Abstract

The FAIR facility will make the region of high net-baryon densities experimentally accessible, where a first-order phase transition is conjectured. We investigate the dynamics of chiral symmetry breaking and the onset of confinement during a heavy-ion collision at large baryochemical potentials within a nonequilibrium chiral fluid dynamics model including effects of dissipation and noise. The order parameters are explicitly propagated and coupled to a fluid dynamically expanding medium of quarks. We demonstrate that the coupled system is strongly influenced by the nonequilibrium dynamics, leading only to a weak growth of the correlation length near the critical point. At the first-order phase transition, spinodal instabilities create domains in the order parameters and large spatial fluctuations in the baryon density within single events. As a consequence we find a clear enhancement of higher flow harmonics in coordinate space at the first-order phase transition in comparison with transitions through the crossover or critical point.