Supergravity inflation on the brane

We study N=1 supergravity inflation in the context of the braneworld scenario. Particular attention is paid to the problem of the onset of inflation at sub-Planckian field values and the ensuing inflationary observables. We find that the so-called problem encountered in supergravity inspired inflationary models can be solved in the context of the braneworld scenario, for some range of the parameters involved. Furthermore, we obtain an upper bound on the scale of the fifth dimension, M₅10^-3M₏, in case the inflationary potential is quadratic in the inflaton field. If the inflationary potential is cubic in, consistency with observational data requires that M₅9. 210^-4M₏.