Inflation with a running spectral index in supergravity

Abstract

The first year Wilkinson Microwave Anisotropy Probe data favor primordial adiabatic fluctuation with a running spectral index with ${n}_{s}>1$ on a large scale and ${n}_{s}<1$ on a smaller scale. The model building of inflation that predicts perturbations with such a spectrum is a challenge, because most models predict fluctuations with either ${n}_{s}>1$ (hybrid inflation) or ${n}_{s}<1$ (new, chaotic, or topological inflation). We give a sensible particle physics model in supergravity that accommodates the desired running of the spectral index using double inflation.