The Giant Inflaton

Abstract

We investigate a new mechanism for realizing slow roll inflation in string theory, based on the dynamics of p anti-D3 branes in a class of mildly warped flux compactifications. Attracted to the bottom of a warped conifold throat, the anti-branes then cluster due to a novel mechanism wherein the background flux polarizes in an attempt to screen them. Once they are sufficiently close, the M units of flux cause the anti-branes to expand into a fuzzy NS5-brane, which for rather generic choices of p/M will unwrap around the geometry, decaying into D3-branes via a classical process. We find that the effective potential governing this evolution possesses several epochs that can potentially support slow-roll inflation, provided the process can be arranged to take place at a high enough energy scale, of about one or two orders of magnitude below the Planck energy; this scale, however, lies just outside the bounds of our approximations.

Figures (4)

• Figure 1: The effective potential $V_{\rm ef\! f}(\psi)$ near the critical value for ${p\over M}\simeq 8 \%$, with only a marginally stable minimum. For smaller $p/M$ there is a more pronounced metastable vacuum, for larger $p/M$, the potential is monotonic.
• Figure 2: The giant inflaton starts as a bound state of $p$ anti-D3's, and expands due to the 3-form flux. Near the slow roll region of the potential, its expansion slows down due to a balance between the 5-brane tension and the dielectric force. Eventually, the 5-brane decays to a supersymmetric state with $M\!-\!p$ D3-branes.
• Figure 3: A stack of $\overline{\rm D3}$-branes polarizes the sea of flux, represented by dashes, leading to a force on a test $\overline{\rm D3}$-brane.
• Figure 4: The giant inflaton trajectory for $B=0.85$ and initial conditions $\psi(0) = .03$ and $\tilde{P}(0)=0.3$, and the corresponding evolution in the log of the scale factor $a$. We see that almost all of the inflation comes from the shoulder region near $\psi=0.7$.