Gravitationally induced particle production in scalartensor f (R ,T ) gravity
Abstract
We explore the possibility of gravitationally generated particle production in the scalartensor representation of f (R ,T ) gravity. Due to the explicit nonminimal curvaturematter coupling in the theory, the divergence of the matter energymomentum tensor does not vanish. We explore the physical and cosmological implications of this property by using the formalism of irreversible thermodynamics of open systems in the presence of matter creation/annihilation. The particle creation rates, pressure, temperature evolution, and the expression of the comoving entropy are obtained in a covariant formulation and discussed in detail. Applied together with the gravitational field equations, the thermodynamics of open systems lead to a generalization of the standard Λ CDM cosmological paradigm, in which the particle creation rates and pressures are effectively considered as components of the cosmological fluid energymomentum tensor. We also consider specific models, and compare the scalartensor f (R ,T ) cosmology with the Λ CDM scenario and the observational data for the Hubble function. The properties of the particle creation rates, of the creation pressures, and entropy generation through gravitational matter production are further investigated in both the low and high redshift limits.
 Publication:

Physical Review D
 Pub Date:
 August 2022
 DOI:
 10.1103/PhysRevD.106.044043
 arXiv:
 arXiv:2205.12545
 Bibcode:
 2022PhRvD.106d4043P
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Theory
 EPrint:
 14 pages, 6 figures. V2: 16 pages, 6 figures