More hilltop inflation models

Abstract

Using analytic expressions, we explore the parameter space for hilltop inflation models with a potential of the form $V_0\pm m^2\phi^2 -a\phi^p$. With the positive sign and p>2 this converts the original hybrid inflation model into a hilltop model, allowing the spectral index to agree with the observed value n=0.95. In some cases the observed value is theoretically favored, while in others there is only the generic prediction $|n-1|\lsim 1$.