Coupling Supersymmetric Nonlinear Sigma Models to Supergravity

TL;DR

This paper demonstrates how to modify supersymmetric nonlinear sigma models to achieve G-invariance of the Kahler potential, enabling consistent coupling to supergravity by enlarging the manifolds and removing U(1) factors.

Contribution

It introduces a deformation method for supersymmetric nonlinear sigma models that ensures G-invariance of the Kahler potential, facilitating supergravity coupling.

Findings

Achieving G-invariance requires dropping U(1) factors from the unbroken subgroup H.

Deformed models can be coupled to supergravity without breaking G invariance.

The method applies to compact Kahler manifolds G/H.

Abstract

It is known that supersymmetric nonlinear sigma models for the compact Kahler manifolds G/H cannot be consistently coupled to supergravity, since the Kahler potentials are not invariant under the G transformation. We show that the supersymmetric nonlinear sigma models can be deformed such that the Kahler potential be exactly G-invariant if and only if one enlarges the manifolds by dropping all the U(1)'s in the unbroken subgroup H. Then, those nonlinear sigma models can be coupled to supergravity without losing the G invariance.