Gravitational induced particle production through a nonminimal
  curvature-matter coupling
  We consider the possibility of a gravitationally induced particle production
through the mechanism of a nonminimal curvature-matter coupling. An interesting
feature of this gravitational theory is that the divergence of the
energy-momentum tensor is nonzero. As a first step in our study we reformulate
the model in terms of an equivalent scalar-tensor theory, with two arbitrary
potentials. By using the formalism of open thermodynamic systems, we interpret
the energy balance equations in this gravitational theory from a thermodynamic
point of view, as describing irreversible matter creation processes. The
particle number creation rates, the creation pressure, and the entropy
production rates are explicitly obtained as functions of the scalar field and
its potentials, as well as of the matter Lagrangian. The temperature evolution
laws of the newly created particles are also obtained. The cosmological
implications of the model are briefly investigated, and it is shown that the
late-time cosmic acceleration may be due to particle creation processes.
Furthermore, it is also shown that due to the curvature--matter coupling,
during the cosmological evolution a large amount of comoving entropy is also
produced.
