Generalized gravity from modified DFT

TL;DR

This paper introduces a modified double field theory (mDFT) framework that derives generalized type IIB supergravity equations, incorporating extra vector fields and maintaining duality symmetries, thus extending the traditional DFT approach.

Contribution

It proposes a modification of DFT by relaxing a covariant derivative condition, leading to a new formulation that reproduces generalized supergravity equations with additional vector fields.

Findings

Modified DFT reproduces generalized type IIB supergravity equations.

Extra vectors in supergravity correspond to new vectors in mDFT.

Duality symmetries are preserved in the modified framework.

Abstract

Recently, generalized equations of type IIB supergravity have been derived from the requirement of classical kappa-symmetry of type IIB superstring theory in the Green-Schwarz formulation. These equations are covariant under generalized T-duality transformations and hence one may expect a formulation similar to double field theory (DFT). In this paper, we consider a modification of the DFT equations of motion by relaxing a condition for the generalized covariant derivative with an extra generalized vector. In this modified double field theory (mDFT), we show that the flatness condition of the modified generalized Ricci tensor leads to the NS-NS part of the generalized equations of type IIB supergravity. In particular, the extra vector fields appearing in the generalized equations correspond to the extra generalized vector in mDFT. We also discuss duality symmetries and a modification of the string charge in mDFT.