Marginal Deformations of Vacua with Massive boson-fermion Degeneracy Symmetry

TL;DR

This paper constructs and analyzes two-dimensional string vacua with Massive Spectrum boson-fermion Degeneracy Symmetry (MSDS), exploring their moduli space, connections to higher-dimensional supergravity, and potential cosmological implications.

Contribution

It explicitly constructs MSDS vacua in Type II and Heterotic strings, studies their deformations, and links them to four-dimensional supergravity and early universe models.

Findings

MSDS vacua can be connected to higher-dimensional superstring vacua via marginal deformations.

Maximally symmetric MSDS vacuum corresponds to N=8 supergravity with flux-induced gauging.

Certain MSDS vacua remain tachyon-free under arbitrary marginal deformations.

Abstract

Two-dimensional string vacua with Massive Spectrum boson-fermion Degeneracy Symmetry (MSDS) are explicitly constructed in Type II and Heterotic superstring theories. The study of their moduli space indicates the existence of large marginal deformations that connect continuously the initial d=2, MSDS vacua to higher-dimensional conventional superstring vacua, where spacetime supersymmetry is spontaneously broken by geometrical fluxes. We find that the maximally symmetric, d=2, Type II MSDS-vacuum, is in correspondence with the maximal, N=8, d=4, gauged supergravity, where the supergravity gauging is induced by the fluxes. This correspondence is extended to less symmetric cases where the initial MSDS symmetry is reduced by orbifolds. We also exhibit and analyse thermal interpretations of some Euclidean versions of the models and identify classes of MSDS vacua that remain tachyon-free under arbitrary marginal deformations about the extended symmetry point. The connection between the two-dimensional MSDS vacua and the resulting four-dimensional effective supergravity theories arises naturally within the context of an adiabatic cosmological evolution, where the very early Universe is conjectured to be described by an MSDS-vacuum, while at late cosmological times it is described by an effective N=1 supergravity theory with spontaneously broken supersymmetry.