Thermal Vacuum Model for Cosmology without Inflaton

Abstract

The previously proposed modification of the standard (flat) inflationary $\Lambda CDM$ model in which the inflaton field(s) and ``dark energy" are replaced by the vacum in expanding Friedmann-Lema\^itre-Robertson-Walker Universe is studied. The expanding joint vacuum of the all ingrediences of matter, including Standard Model particles and a dark matter sector, is treated as a thermal equilibrium state at temporal Gibbons-Hawking temperature, proportional to the Hubble parameter, and chemical potentials equal to particle masses. This theory provides not only the new mechanism of inflation and its graceful exit, but also explains acceleration of expansion for the late Universe. The formalism can be combined with the anomalous quantum gravity effects leading to a viable baryogenesis mechanism and certain bounds on dark matter particle masses and lifetimes.