de Sitter vacua in no-scale supergravities and Calabi-Yau string models

TL;DR

This paper analyzes the conditions for metastable de Sitter vacua with broken supersymmetry in string models, focusing on the role of the Kahler potential and no-scale structure in heterotic and orientifold compactifications.

Contribution

It provides a general criterion for non-tachyonic scalar partners of the Goldstino based on the Kahler potential and explores how no-scale properties restrict vacuum stability in string models.

Findings

Positive sGoldstino masses are achievable only in specific compactifications.

Subleading Kahler potential corrections can lift scalar masses.

No-scale structure imposes severe restrictions on metastable vacua.

Abstract

We perform a general analysis on the possibility of obtaining metastable vacua with spontaneously broken N=1 supersymmetry and non-negative cosmological constant in the moduli sector of string models. More specifically, we study the condition under which the scalar partners of the Goldstino are non-tachyonic, which depends only on the Kahler potential. This condition is not only necessary but also sufficient, in the sense that all of the other scalar fields can be given arbitrarily large positive square masses if the superpotential is suitably tuned. We consider both heterotic and orientifold string compactifications in the large-volume limit and show that the no-scale property shared by these models severely restricts the allowed values for the `sGoldstino' masses in the superpotential parameter space. We find that a positive mass term may be achieved only for certain types of compactifications and specific Goldstino directions. Additionally, we show how subleading corrections to the Kahler potential which break the no-scale property may allow to lift these masses.