Thermal vacuum model for cosmology without inflaton

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 vacuum in expanding Friedmann-Lemaître-Robertson-Walker Universe is studied. The expanding joint vacuum of all ingredients 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 applied to the early Universe provided the new mechanism of inflation and its graceful exit accompanied by particles production. Here, it is shown that the same idea applied to the late Universe explains acceleration of expansion and gives a natural solution to the “cosmological constant problem”. Moreover, this formalism can be combined with the anomalous quantum gravity effects leading to a viable baryogenesis mechanism and producing certain restrictions on the mass spectrum for dark matter particles.