Abstract
We discuss inflaton decays and reheating in no-scale Starobinsky-like models of inflation, calculating the effective equation-of-state parameter, w, during the epoch of inflaton decay, the reheating temperature, Treh, and the number of inflationary e-folds, N*, comparing analytical approximations with numerical calculations. We then illustrate these results with applications to models based on no-scale supergravity and motivated by generic string compactifications, including scenarios where the inflaton is identified as an untwisted-sector matter field with direct Yukawa couplings to MSSM fields, and where the inflaton decays via gravitational-strength interactions. Finally, we use our results to discuss the constraints on these models imposed by present measurements of the scalar spectral index ns and the tensor-to-scalar perturbation ratio r, converting them into constraints on N*, the inflaton decay rate and other parameters of specific no-scale inflationary models.
Highlights
Following the 2013 Planck data release, three of us re-examined [39,40,41] no-scale models of inflation based on a Kahler potential of the form
We have recently studied various phenomenological aspects of such no-scale models of inflation, stressing how they could be embedded in compactifications of string theory [53]
We showed that different no-scale supergravity models led to different estimates of the reheating temperature after inflation, Treh, and found a connection between the reheating temperature and the possible mechanism of supersymmetry breaking
Summary
In the slow-roll approximation and assuming entropy conservation after reheating, the number of e-folds to the end of inflation can be expressed as [1, 2, 64, 72]. 1018 GeV is the reduced Planck mass) is nearly scale-invariant for large values of the inflaton field φ: for φ ≫ MP , V. This value is a good first approximation to V∗. In the range 50 < N∗ < 70, this yields 0.728m2MP2 < V∗ < 0.734m2MP2 , a result that is in good agreement with the more exact values that we obtain from numerical integration of the equations of motion.
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