Gómez Nicola, ÁngelGalán González, V.2023-06-202023-06-201999-03-110370-269310.1016/S0370-2693(99)00067-2https://hdl.handle.net/20.500.14352/59584© 1999 Elsevier Science B.V. We are grateful to T. Evans and R. Rivers for countless and fruitful discussions, as well as to R.F. Alvarez-Estrada, A. Dobado and A.L. Maroto for providing useful references and comments. A.G.N wishes to thank the Imperial College group for their kind hospitality during his stay there and has received financial support through a postdoctoral fellowship of the Spanish Ministry of Education and CICYT, Spain, project AEN97-1693.We extend chiral perturbation theory to study a meson gas out of thermal equilibrium. Assuming that the system is initially in equilibrium at T-i < T-c and working within the Schwinger-Keldysh contour technique, we define consistently the time-dependent temporal and spatial pion decay functions, the counterparts of the pion decay constants, and calculate them to next to leading order. The link with curved space-time QFT allows to establish nonequilibrium renormalisation. The short-time behaviour and the applicability of our model to a heavy-ion collision plasma are also discussed in this work.engjournal articlehttp://dx.doi.org/10.1016/S0370-2693(99)00067-2http://www.sciencedirect.comopen access51-73Qcd phase-TransitionFinite-temperatureEquilibriumEvolutionEnergyFieldFísica-Modelos matemáticosFísica matemática