Gauge and Modulus Inflation from 5D Orbifold SUGRA

Abstract

We study the inflationary scenarios driven by a Wilson line field - the fifth component of a 5D gauge field and corresponding modulus field, within S^1/Z_2 orbifold supergravity (SUGRA). We use our off shell superfield formulation and give a detailed description of the issue of SUSY breaking by the F-component of the radion superfield. By a suitably gauged U(1)R symmetry and including couplings with compensator supermultiplets and a linear multiplet, we achieve a self consistent radion mediated SUSY breaking of no scale type. The inflaton 1-loop effective potential has attractive features needed for successful inflation. An interesting feature of both presented inflationary scenarios are the red tilted spectra with ns~0.96. For gauge inflation we obtain a significant tensor to scalar ratio r~0.1 of the density perturbations, while for the modulus inflation r is strongly suppressed.