Minimal gauge inflation

We consider a gauge inflation model in the simplest orbifold M4 x S1/Z2 with the minimal non-Abelian SU(2) hidden sector gauge symmetry. The inflaton potential is fully radiatively generated solely by gauge self-interactions. Following the virtue of gauge inflation idea, the inflaton, a part of the five dimensional gauge boson, is automatically protected by the gauge symmetry and its potential is stable against quantum corrections. We show that the model perfectly fits the recent cosmological observations, including the recent WMAP 5-year data, in a wide range of the model parameters. In the perturbative regime of gauge interactions (g_{4D} <= 1/(2pi R M_P)) with the moderately compactified radius (10 <= R M_P <= 100) the anticipated magnitude of the curvature perturbation power spectrum and the value of the corresponding spectral index are in perfect agreement with the recent observations. The model also predicts a large fraction of the gravitational waves, negligible non-Gaussianity, and high enough reheating temperature.