CHALLENGING ΛCDM WITH SCALAR-TENSOR f(R, T) GRAVITY AND THERMODYNAMICS OF IRREVERSIBLE MATTER CREATION

We investigate gravitationally-induced particle production in the equivalent scalar-tensor representation of f(R, T) gravity. In this theory, the matter energy-momentum tensor may not be conserved due to a non-minimal curvature-matter coupling. As such, we explore the consequences of such a non-conservation within the scope of particle production by using the formalism of irreversible thermodynamics of open systems. Accordingly, we obtain the expressions for the particle creation rate and for the creation pressure. Finally, we explore the de Sitter solution with a constant and non-constant matter energy density and determine the explicit expressions for the two scalar fields and both creation rate and pressure.