Inflaton Decay in No-Scale Supergravity and Starobinsky-like Models

We consider the decay of the inflaton in Starobinsky-like models arising from either an (Formula presented.) theory of gravity or (Formula presented.) no-scale supergravity models. If Standard Model matter is simply introduced to the (Formula presented.) theory, the inflaton (which appears when the theory is conformally transformed into the Einstein frame) couples to matter predominantly in Standard Model Higgs kinetic terms. This will typically lead to a reheating temperature of ∼3 × (Formula presented.) GeV. However, if the Standard Model Higgs is conformally coupled to curvature, the decay rate may be suppressed and vanishes for conformal coupling (Formula presented.). Nevertheless, the inflaton decays through the conformal anomaly, leading to a reheating temperature of the order of (Formula presented.) GeV. The Starobinsky potential may also arise in no-scale supergravity. In this case, the inflaton decays if there is a direct coupling of the inflaton to matter in the superpotential or to gauge fields through the gauge kinetic function. We also discuss the relation between the theories and demonstrate the correspondence between the no-scale models and the conformally coupled (Formula presented.) theory (with (Formula presented.)).