Stringy corrections to Kahler potentials, SUSY breaking, and the cosmological constant problem

Abstract

The moduli of N=1 compactifications of IIB string theory can be stabilized by a combination of fluxes (which freeze complex structure moduli and the dilaton) and nonperturbative superpotentials (which freeze Kahler moduli), typically leading to supersymmetric AdS vacua. We show that stringy corrections to the Kahler potential qualitatively alter the structure of the effective scalar potential even at large volume, and can give rise to non-supersymmetric vacua including metastable de Sitter spacetimes. Our results suggest an approach to solving the cosmological constant problem, so that the scale of the 1-loop corrected cosmological constant can be much smaller than the scale of supersymmetry breaking.

Figures (2)

• Figure 1: General form of scalar potential for Kähler moduli. For convenience, only one Kähler parameter is shown. (A) Potential with non-perturbative superpotential generated by 3-brane instantons or gaugino condensation. (B) Effects of the $\alpha'^3$ correction to the Kähler potential. The scalar potential approaches zero from above. The situation depicted is for sufficiently small $W_0$ -- a supersymmetric AdS minimum persists. The dashed line is the location of the (naive) singularity in the potential at $V = \xi$.
• Figure 2: Non-supersymmetric Minkowski vacuum when the flux contribution to the superpotential, $W_0$, is large. An accurate description of the shaded region requires inclusion of additional corrections, but for a range of parameters the minimum lies in a region where the leading terms in the scalar potential, $V$, are sufficient. The dashed line is the location of the (naive) singularity in $V$ at $V = \xi$, after including $\alpha'^3$ corrections to the Kähler potential.