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Gravitationally induced particle production in scalar-tensor f(R,T) gravity

M. Pinto, T. Harko, F. S. N. Lobo

We explore the possibility of gravitationally generated particle production in the scalar-tensor representation of f(R,T) gravity. Due to the explicit nonminimal curvature-matter coupling in the theory, the divergence of the matter energy-momentum 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 ΛCDM cosmological paradigm, in which the particle creation rates and pressures are effectively considered as components of the cosmological fluid energy-momentum tensor. We also consider specific models, and compare the scalar-tensor f(R,T) cosmology with the ΛCDM 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.

General Relativity and Quantum Cosmology; Astrophysics - Cosmology and Nongalactic Astrophysics; High Energy Physics - Theory

Physical Review D
Volume 106, Issue 4
2022 August

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia