Speaker
Description
Inflaton couplings to the radiation bath source inflaton fluctuations that are predominantly thermal in origin. In the context of pseudoscalar couplings, a chemical potential is induced in the bath due to non-conserved charges, which significantly modifies both the thermal friction acting on the inflaton and its associated fluctuations. In particular, the chemical potential alters the fluctuation-dissipation theorem and thereby modifies the resulting power spectrum, making it model-dependent. In previous work, we captured this effect on the friction and noise coefficients, demonstrating that the corrections can be order-one and thus non-negligible. Building on these results, we systematically investigate the non-Gaussianities generated at leading order in the inflaton-bath coupling constants, revealing multiple novel contributions to the primordial bispectrum. One such source, not previously considered, stems from chemical-potential-induced higher-order corrections to the friction term. Incorporating these corrections, we further show that thermal expectation values reduce to a classical limit in the zero-width limit for bath correlators, with implications for the shape and amplitude of the primordial bispectrum.