A Delicate Universe

Abstract

We investigate whether explicit models of warped D-brane inflation are possible in string compactifications. To this end, we study the potential for D3-brane motion in a warped conifold that includes holomorphically-embedded D7-branes involved in moduli stabilization. The presence of the D7-branes significantly modifies the inflaton potential. We construct an example based on a very simple and symmetric embedding due to Kuperstein, z_1 = constant, in which it is possible to fine-tune the potential so that slow roll inflation can occur. The resulting model is rather delicate: inflation occurs in the vicinity of an inflection point, and the cosmological predictions are extremely sensitive to the precise shape of the potential.

Figures (2)

• Figure 1: Cartoon of an embedded stack of D7-branes wrapping a four-cycle, and a mobile D3-brane, in a warped throat region of a compact Calabi-Yau.
• Figure 2: Inflaton potential $\mathbb{V}(\phi)$. Compactification data: $n=8$, $\phi_\mu = \frac{1}{4}$, $A_0 = 1$, $W_0= - 3.432 \times 10^{-4}$, $D = 1.2 \times 10^{-8}$, which imply $a \sigma_0 \approx 10.1$.