Inflation with a running spectral index in supergravity

The first year Wilkinson Microwave Anisotropy Probe data favor primordial adiabatic fluctuation with a running spectral index with nₛ>1 on a large scale and nₛ<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 nₛ>1 (hybrid inflation) or nₛ<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.