Inflation from Wrapped Branes

Abstract

We show that the use of higher dimensional wrapped branes can significantly extend the inflaton field range compared to brane inflation models which use D3-branes. We construct a simple inflationary model in terms of 5-branes wrapping a 2-cycle and traveling towards the tip of the Klebanov-Strassler throat. Inflation ends when the branes reach the tip of the cone and self-annihilate. Assuming a quadratic potential for the brane it is possible to match the CMB data in the DBI regime, but we argue that the backreaction of the brane is important and cannot be neglected. This scenario predicts a strong non-Gaussian signal and possibly detectable gravitational waves.

Figures (2)

• Figure 1: A $D$5-brane wrapping a two-cycle $p$ times that shrinks to a point. We are showing here the system in Cartesian coordinates where the $D$5 is at a fixed radius $\rho_0$. Below $\rho_0$, there are $M-p$ units of $F_3$ while above it the original background $M$ units remain. When the radius reaches the (accordingly warped) string scale, a tachyon develops on the brane. One can think of this as brane-antibrane annihilation between antipodal part of the brane on the $S^2$ it wraps.
• Figure 2: We show the $\rho$ direction together with the $S^2$ and $S^3$. There are $M$ units of $F_3$ threading through the $S^3$. We wrap the $D$5-brane on the $S^2$ at some fixed position on the $\rho$ axis. Below that value of $\rho$ (below the dark line in the picture) there is one less unit of $F_3$ threading through the $S^3$.