Inflating in a Better Racetrack

Abstract

We present a new version of our racetrack inflation scenario which, unlike our original proposal, is based on an explicit compactification of type IIB string theory: the Calabi-Yau manifold IP 4 [1,1,1,6,9] . The axion-dilaton and all complex structure moduli are stabilized by fluxes. The remaining 2 Kähler moduli are stabilized by a nonperturbative superpotential, which has been explicitly computed. For this model we identify situations for which a linear combination of the axionic parts of the two Kähler moduli acts as an inflaton. As in our previous scenario, inflation begins at a saddle point of the scalar potential and proceeds as an eternal topological inflation. For a certain range of inflationary parameters, we obtain the COBEnormalized spectrum of metric perturbations and an inflationary scale of M = 3 × 10 14 GeV. We discuss possible changes of parameters of our model and argue that anthropic considerations favor those parameters that lead to a nearly flat spectrum of inflationary perturbations, which in our case is characterized by the spectral index n s = 0.95.

Inflation and String Theory

“…We give detailed analyses of N-flation [530] and axion monodromy inflation [34]. In §5.5, we describe models in which the inflaton is a Kähler modulus (or the associated axion), including racetrack inflation [618,619] and inflationary scenarios in large volume compactifications [43,620,621]. Finally, in §5.6, we look at dissipative effects as a source of inflation and critically assess the prospects for dissipative inflation in string compactifications [622][623][624][625].…”

Systematics of moduli stabilization, inflationary dynamics and power spectrum

“…An example of inflationary model where only the complex structure moduli and the axion-dilaton are stabilized can be found in [3] 3 .…”

“…For the model in [3], the volume is V = 99 in string units. Thus, the change in the spectrum from complex-structure moduli and the axion-dilaton is of order 10 −2 .…”

“…Thus, the change in the spectrum from complex-structure moduli and the axion-dilaton is of order 10 −2 . Since the current experiment can measure δP/P up to order 10 −3 − 10 −2 , it is necessary to calculate this effect in model [3] 4 .…”

“…As an example, in [3], four fields were relevant to generating inflation. Following such a system is a complex task, and it is not unreasonable to ask whether there are ways to reduce the number of inflaton fields that need to be tracked.…”