Perturbative quantum gravity in double field theory

TL;DR

This paper investigates perturbative quantum gravity within double field theory, demonstrating consistency with known results, exploring gauge choices, and showing that the theory reproduces key scattering amplitudes and string corrections.

Contribution

It provides a detailed analysis of perturbative quantum gravity using double field theory, including gauge choices, unitarity, and amplitude reconstruction, with applications to string corrections.

Findings

Decoupling of ghost-like scalar in covariant gauge confirmed

Most tree-level scattering amplitudes reproduced by double field theory

Derived expressions for string corrections from double field theory

Abstract

We study perturbative general relativity with a two-form and a dilaton using the double field theory formulation which features explicit index factorisation at the Lagrangian level. Explicit checks to known tree level results are performed. In a natural covariant gauge a ghost-like scalar which contributes even at tree level is shown to decouple consistently as required by perturbative unitarity. In addition, a lightcone gauge is explored which bypasses the problem altogether. Using this gauge to study BCFW on-shell recursion, we can show that most of the D-dimensional tree level S-matrix of the theory, including all pure graviton scattering amplitudes, is reproduced by the double field theory. More generally, we argue that the integrand may be reconstructed from its single cuts and provide limited evidence for off-shell cancellations in the Feynman graphs. As a straightforward application of the developed technology double field theory-like expressions for four field string corrections are derived.