On the Coupling of Gravitons to Matter

TL;DR

This paper develops a method to compute graviton-matter scattering amplitudes using gauge theory relationships, including cases with massive gravitons and unconventional color-kinematics decompositions.

Contribution

It introduces a novel construction of tree-level graviton-matter amplitudes via gauge theory partial amplitudes, incorporating massive gravitons and new color-kinematics structures.

Findings

Constructed amplitudes with gravitons coupled to vectors and fermions

Presented examples with massive graviton exchange in compact dimensions

Proposed an unconventional color-kinematics decomposition in gauge theories

Abstract

Using relationships between open and closed strings, we present a construction of tree-level scattering amplitudes for gravitons minimally coupled to matter in terms of gauge theory partial amplitudes. In particular, we present examples of amplitudes with gravitons coupled to vectors or to a single fermion pair. We also present two examples with massive graviton exchange, as would arise in the presence of large compact dimensions. The gauge charges are represented by flavors of dynamical scalars or fermions. This also leads to an unconventional decomposition of color and kinematics in gauge theories.