Supersymmetry Breaking due to Moduli Stabilization in String Theory

TL;DR

This paper explores how different moduli stabilization mechanisms in string theory influence supersymmetry breaking patterns, with implications for cosmology and particle physics, including addressing the gravitino problem.

Contribution

It demonstrates that strong moduli stabilization results in a distinct supersymmetry breaking pattern, with implications for phenomenology and cosmology, especially in resolving the gravitino and tachyonic stau issues.

Findings

Strong stabilization leads to scalar masses of order the gravitino mass.

Gaugino masses are suppressed at tree level but generated radiatively.

A large gravitino mass (~100 TeV) resolves cosmological problems.

Abstract

We consider the phenomenological consequences of fixing compactification moduli. In the simplest KKLT constructions, stabilization of internal dimensions is rather soft: weak scale masses for moduli are generated, and are of order m_\sigma ~ m_{3/2}. As a consequence one obtains a pattern of soft supersymmetry breaking masses found in gravity and/or anomaly mediated supersymmetry breaking (AMSB) models. These models may lead to destabilization of internal dimensions in the early universe, unless the Hubble constant during inflation is very small. Fortunately, strong stabilization of compactified dimensions can be achieved by a proper choice of the superpotential (e.g in the KL model with a racetrack superpotential). This allows for a solution of the cosmological moduli problem and for a successful implementation of inflation in supergravity. We show that strong moduli stabilization leads a very distinct pattern of soft supersymmetry breaking masses. In general, we find that soft scalar masses remain of order the gravitino mass, while gaugino masses nearly vanish at the tree level, i.e. they are of order m_{3/2}^2/m_\sigma. Radiative corrections generate contributions to gaugino masses reminiscent of AMSB models and a decoupled spectrum of scalars reminiscent of split-supersymmetry. This requires a relatively large gravitino mass ~ O(100) TeV, resolving the cosmological gravitino problem and problems with tachyonic staus in AMSB models.