Kähler Stabilized, Modular Invariant Heterotic String Models

Abstract

We review the theory and phenomenology of effective supergravity theories based on orbifold compactifications of the weakly-coupled heterotic string. In particular, we consider theories in which the four-dimensional theory displays target space modular invariance and where the dilatonic mode undergoes Kähler stabilization. A self-contained exposition of effective Lagrangian approaches to gaugino condensation and heterotic string theory is presented, leading to the development of the models of Binétruy, Gaillard and Wu. Various aspects of the phenomenology of this class of models are considered. These include issues of supersymmetry breaking and superpartner spectra, the role of anomalous U (1) factors, issues of flavor and R-parity conservation, collider signatures, axion physics, and early universe cosmology. For the vast majority of phenomenological considerations the theories reviewed here compare quite favorably to other string-derived models in the literature. Theoretical objections to the framework and directions for further research are identified and discussed.

Towards matter ination in heterotic string theory

“…These are an important ingredient for successful moduli stabilization in string theory and in heterotic models they are crucial in order to stabilize the dilaton. The stabilization scheme which we will employ here is known as Kähler stabilization [94][95][96][97]. It relies on non-perturbative corrections to the superpotential from gaugino condensation in combination with non-perturbative corrections to the Kähler potential.…”

“…The relation between the linear and the chiral multiplet formalism gets modified by both perturbative and non-perturbative effects [94][95][96][97]:…”

“…The differential equation and boundary condition ensure canonical normalization of the Einstein term and the correct behaviour in the weak-coupling limit → 0, respectively. Following [94][95][96][97], we parametrize f ( ) as…”

Supersymmetry and superstring phenomenology

“…This mechanism for stabilizing the dilaton is known as "Kähler" stabilization. The attractive features of Kähler stabilized, T self-dual heterotic string models can be summarized as follows [21] • In contrast with models that stabilize the dilaton using more than one gaugino condensate (and adjusting their relative β-functions), there is no difficulty in generating a positive semidefinite potential.…”

Mirage models confront the LHC. III. Deflected mirage mediation

“…In this scenario, the dynamical supersymmetry breaking triggered by strong coupling in a hidden sector is connected to the observable sector in a manner that is suppressed, thus allowing loop-induced Weyl anomaly contributions to soft supersymmetry breaking to be of comparable size to tree-level contributions. Surprisingly, this is a common outcome of many well-motivated string constructions [4][5][6]. The phenomenology of these models, in terms of LHC observables, has been recently described in [7] for heterotic models, and in [8] for Type IIB orientifold models.…”