Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Supersymmetry Breaking due to Moduli Stabilization in String Theory

Andrei Linde, Yann Mambrini, Keith A. Olive

TL;DR

The paper analyzes how moduli stabilization in string theory shapes supersymmetry breaking. It compares KKLT and KL constructions, showing that strong stabilization in KL (with $m_\sigma \gg m_{3/2}$) drives the SUSY-breaking term $D_\rho W$ to be much smaller than $m_{3/2}$, so gaugino masses are largely generated by anomaly mediation while scalar masses remain at $m_{3/2}$. This produces a split-SUSY–like spectrum, avoids the cosmological moduli and gravitino problems, and allows high-scale inflation without destabilizing the compact dimensions. The results provide a concrete, testable pattern for soft terms in string-motivated scenarios and have implications for collider and cosmological phenomenology.

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_σ~ 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_σ. 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.

Supersymmetry Breaking due to Moduli Stabilization in String Theory

TL;DR

The paper analyzes how moduli stabilization in string theory shapes supersymmetry breaking. It compares KKLT and KL constructions, showing that strong stabilization in KL (with ) drives the SUSY-breaking term to be much smaller than , so gaugino masses are largely generated by anomaly mediation while scalar masses remain at . This produces a split-SUSY–like spectrum, avoids the cosmological moduli and gravitino problems, and allows high-scale inflation without destabilizing the compact dimensions. The results provide a concrete, testable pattern for soft terms in string-motivated scenarios and have implications for collider and cosmological phenomenology.

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_σ~ 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_σ. 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.

Paper Structure

This paper contains 4 sections, 45 equations, 2 figures.

Table of Contents

  1. Introduction
  2. The KKLT and KL models
  3. Soft masses in the KKLT and KL models
  4. Conclusions

Figures (2)

  • Figure 1: Scalar potential of the KKLT model for the values of the parameters $A =1$, $a = 1$ and $W_0=10^{-12}$ before and after uplifting. The potential has been multiplied by a factor of $10^{29}$ for clarity.
  • Figure 2: Scalar potential of the KL model for the values of the parameters $A=B =1,\,a = 0.1,\,b = 0.05$. The potential has been multiplied by a factor of $10^{7}$ for clarity. The effect of uplifting is so small as compared to the height of the barrier in this model that one cannot distinguish an uplifted and non-uplifted potential on the scale of this figure.