Gravitational waves in the presence of a non-minimal curvature-matter coupling are analysed, both in the Newman–Penrose and perturbation theory formalisms. Considering a cosmological constant as a...

Weyl gravity in the presence of a non-minimal matter-curvature coupling is presented. Some properties arising from the non-metricity give rise to a second order theory whose vacuum is compatible with a cosmological constant, under conditions on the vector field.

We derive the Boltzmann equation in the context of a gravity theory with nonminimal coupling between matter and curvature. We show that as the energy-momentum tensor is not conserved in these theories, it follows a condition on the normalization of a homogeneous distribution function. The Boltzmann H-theorem is preserved such that the entropy vector flux is still a nondecreasing function in these theories. The case of a homogeneous and isotropic universe is analyzed.

We consider a nonminimally coupled curvature-matter gravity theory at the Solar System scale. Both a fifth force of Yukawa type and a further non-Newtonian extra force that arises from the nonminimal coupling are present in the solar interior and in the solar atmosphere up to interplanetary space. The extra force depends on the spatial gradient of space-time curvature $R$. The conditions under which the effects of such forces can be screened by the chameleon mechanism and be made consistent with Cassini measurement of parametrized post-Newtonian parameter $\gamma$ are examined. Constraints from spectroscopic observations of the solar atmosphere are also taken into account. This consistency analysis requires a specific study of the Sun’s dynamical contribution to the arising forces at all its layers.