Gauge and modulus inflation from 5D orbifold SUGRA

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)/Z2 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.