Reheating via a generalized nonminimal coupling of curvature to matter

Abstract

In this work one shows that a generalized non-minimal coupling between geometry and matter is compatible with Starobinsky inflation and leads to a successful process of preheating, a reheating scenario based on the production of massive particles via parametric resonance. The model naturally extends the usual preheating mechanism, which resorts to an ad-hoc scalar curvature-dependent mass term for a scalar field χ, and also encompasses a previously studied preheating channel based upon a non-standard kinetic term.

Modified Friedmann equation from nonminimally coupled theories of gravity

“…Indeed, these can be coupled, for instance, in a nonminimal way [3] (see also Refs. [4][5][6] for early proposals in cosmology), a fact that can have a bearing on the dark matter [7,8] and dark energy [9,10] problems, as well as inflation [11,12] and structure formation [13]. This putative nonminimal coupling modifies the well-known energy conditions [14] and can give rise to several implications, from Solar System [15] and stellar dynamics [16][17][18][19] to close time-like curves [20] and wormholes [21].…”

Wormholes and Time-Machines in Nonminimally Coupled Matter-Curvature Theories of Gravity

“…Moreover, these models allow for the mimicking of dark matter profiles in galaxies [10] and clusters of galaxies [11], as well as of dark energy at cosmological scales [12]. It was also shown that one can obtain somewhat more natural conditions for preheating in inflationary models [13] and that the coupling between curvature and matter is equivalent, under conditions, to an effective pressure which leads, in the weak field limit, to a generalized Newtonian potential [14].…”

Mimicking the cosmological constant: Constant curvature spherical solutions in a nonminimally coupled model

“…This possibility can have deep phenomenological implications: in particular, it would imply that regions with high curvature (which, in GR, are related to regions of high energy density or pressure) could lead to considera ble deviations from the dynamics predicted by Einstein's theory [17]. A wide range of results has arisen from this hypothesis, including the formal equivalence with a multi-scalar-tensor theory [18], the impact on solar observables [19], the possibility to account for dark matter [20], post-inflationary reheating [21] or the current accelerated expansion of the universe [22].…”