Speaker
Description
Cold inflation provides an elegant explanation for the near homogeneity and flatness of the Universe. However, the simplest large-field models are disfavored by Planck CMB data, and fitting current observations typically requires inflationary potentials that appear fine-tuned from an effective field theory perspective. The curvaton mechanism alleviates this tension: a light spectator field acquires nearly scale-invariant isocurvature fluctuations during inflation and later converts them into the adiabatic perturbations observed today. Yet the scenario generally remains weakly predictive, since the initial curvaton displacement, which sets its energy density, is usually independent of its decay width. We show that under minimal assumptions these quantities can become dynamically linked. If the curvaton couples linearly to the Standard Model, the thermal bath displaces it from its vacuum expectation value by an amount determined by the inflationary scale and the reheating history. Requiring this thermally induced displacement to reproduce the observed scalar power spectrum then fixes the curvaton-matter coupling in terms of the curvaton mass, making the scenario more predictive.