Inflation with a running spectral index in supergravity

Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan (Dated: June 4, 2005) Abstract The first year Wilkinson Microwave Anisotropy Probe data favors 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.