Successful Supersymmetric Inflation
G. G. Ross, S. Sarkar
TL;DR
Ross and Sarkar argue that inflation can arise naturally within effective supergravity using a gauge-singlet inflaton in a hidden sector. They show that an inflationary scale around $V^{1/4}\sim 10^{14}$ GeV is compatible with SUSY-breaking dynamics and COBE data, yielding a low reheat temperature $T_R$ that avoids gravitino overproduction and a negligible tensor contribution with a tilted scalar spectrum. A concrete model with $I(\Phi)=\frac{\Delta^2}{M}(\Phi-\Phi_0)^2$ yields $\Delta/M\sim 1.4\times10^{-4}$, $V^{1/4}\sim 3\times10^{14}$ GeV, $m_\phi\sim 5\times10^{10}$ GeV, and $T_R\sim 1.5\times10^{5}$ GeV, consistent with gravitino bounds and COBE normalization. The paper also addresses gravitino production from inflaton decay (finding suppression) and the Polonyi/moduli problem, offering potential remedies such as high-scale moduli masses or coincident minima, while noting remaining challenges for light moduli like the dilaton. Overall, the work advocates a natural, single-scale SUSY-inflation scenario with clear observational predictions for the CMB and structure formation, while outlining key cosmological caveats in string-inspired settings.
Abstract
We reconsider the problems of cosmological inflation in effective supergravity theories. A singlet field in a hidden sector is demonstrated to yield an acceptable inflationary potential, without fine tuning. In the simplest such model, the requirement of generating the microwave background anisotropy measured by COBE fixes the inflationary scale to be about $10^{14}$ GeV, implying a reheat temperature of order $10^{5}$ GeV. This is low enough to solve the gravitino problem but high enough to allow baryogenesis after inflation. Such consistency requires that the generation of gravitational waves be negligible and that the spectrum of scalar density perturbations depart significantly from scale-invariance, thus improving the fit to large-scale structure in an universe dominated by cold dark matter. We also consider the problems associated with gravitino production through inflaton decay and with other weakly coupled fields such as the moduli encountered in (compactified) string theories.