Reheating of the universe after inflation with f(phi)R gravity

TL;DR

This paper demonstrates that in f(phi)R gravity models, the universe's reheating occurs spontaneously without explicit couplings, as the inflaton naturally couples to matter fields through derivatives of f(phi) at its vacuum expectation value.

Contribution

It introduces a novel spontaneous reheating mechanism in f(phi)R gravity models, eliminating the need for explicit inflaton-matter couplings.

Findings

Reheating occurs spontaneously in broad f(phi)R models.

Couplings arise from derivatives of f(phi) at the vev.

Inflaton decays into non-conformally invariant fields.

Abstract

We show that reheating of the universe occurs spontaneously in a broad class of inflation models with f(phi)R gravity (phi is inflaton). The model does not require explicit couplings between phi and bosonic or fermionic matter fields. The couplings arise spontaneously when phi settles in the vacuum expectation value (vev) and oscillates, with coupling constants given by derivatives of f(phi) at the vev and the mass of resulting bosonic or fermionic fields. This mechanism allows inflaton quanta to decay into any fields which are not conformally invariant in f(phi)R gravity theories.