Hawking--Unruh Radiation from the relics of the cosmic quark hadron phase transition

Abstract

It is entirely plausible that during the primordial quark-hadron transition, microseconds after the Big Bang, the universe may experience supercooling accompanied by mini inflation leading to a first-order phase transition from quarks to hadrons. The relics, in the form of quark nuggets expected to consist of Strange Quark Matter, with a baryon number beyond a critical value will survive. It is conjectured that color confinement turns the physical vacuum to an event horizon for quarks and gluons. The horizon can be crossed only by quantum tunnelling. The process just mentioned is the QCD counterpart of Hawking radiation from gravitational black holes. Thus, when the Hawking temperature of the quark nuggets gets turned off, tunnelling will stop and the nuggets will survive forever. The baryon number and the mass of these nuggets are derived using this theoretical format. The results agree well with the prediction using other phenomenological models. Further, the variation of Hawking temperature as a function of baryon number and mass of the nugget mimicks chiral phase transition, somewhat similar to the QCD phase transition just described. Finally the strange quark nuggets may well be the candidates of baryonic dark matter.