# Ambitwistor string amplitudes in light-like linear dilaton background

## TL;DR

This paper explores graviton scattering amplitudes within ambitwistor string theory in a light-like linear dilaton background, revealing that three-point amplitudes match superstring theory while higher-point amplitudes differ but still satisfy scattering equations.

## Contribution

It demonstrates how graviton amplitudes are affected by a light-like linear dilaton background and introduces a modified momentum conservation law impacting amplitude calculations.

## Key findings

- Three-graviton amplitude matches superstring theory.
- Higher-point amplitudes differ but satisfy scattering equations.
- Modified momentum conservation law influences perturbative amplitudes.

## Abstract

Using the ambitwistor string theory, we study graviton scattering amplitudes in a light-like linear dilaton background of ten-dimensional supergravity. At the tree level, we find that the three-graviton amplitude coincides with the type II superstring theory, and the four or more graviton amplitudes differ from the superstring theory but satisfy the scattering equations. Due to a modified momentum conservation law different at each order in genus expansion, a non-zero amplitude is determined solely from the particular order in perturbation theory without further corrections.