Red spectral tilt and observable gravity waves in shifted hybrid inflation

Abstract

We consider supersymmetric shifted hybrid inflation models with a red-tilted scalar spectral index ${n}_{s}$ in agreement with the WMAP 7-yr central value. If nonminimal supergravity corrections are included, these models can also support a tensor-to-scalar ratio as large as $r\ensuremath{\simeq}0.02$, which may be observable by the Planck Satellite. In contrast to the standard supersymmetric hybrid inflation scenario, topological defects produced via gauge symmetry breaking are inflated away in the shifted version of the theory.