General dissipation coefficient in low-temperature warm inflation

Abstract

In generic particle physics models, the inflaton field is coupled to other\nbosonic and fermionic fields that acquire large masses during inflation and may\ndecay into light degrees of freedom. This leads to dissipative effects that\nmodify the inflationary dynamics and may generate a nearly-thermal radiation\nbath, such that inflation occurs in a warm rather than supercooled environment.\nIn this work, we perform a numerical computation and obtain expressions for the\nassociated dissipation coefficient in supersymmetric models, focusing on the\nregime where the radiation temperature is below the heavy mass threshold. The\ndissipation coefficient receives contributions from the decay of both on-shell\nand off-shell degrees of freedom, which are dominant for small and large\ncouplings, respectively, taking into account the light field multiplicities. In\nparticular, we find that the contribution from on-shell decays, although\nBoltzmann-suppressed, can be much larger than that of virtual modes, which is\nbounded by the validity of a perturbative analysis. This result opens up new\npossibilities for realizations of warm inflation in supersymmetric field\ntheories.\n