Strings on Celestial Sphere

TL;DR

This paper maps superstring scattering amplitudes onto conformal correlation functions on a celestial sphere, revealing a new perspective on string interactions through celestial conformal field theory.

Contribution

It introduces a novel framework translating superstring amplitudes into celestial conformal correlators, emphasizing the role of Lorentz symmetry and Mellin transforms in this mapping.

Findings

Four-point amplitudes for gauge bosons and gravitons are expressed as celestial conformal correlators.

The Lorentz group acts as the conformal group on the celestial sphere, linking spacetime symmetries to conformal symmetries.

Mellin transforms relate particle energies to conformal dimensions, enabling a new representation of string amplitudes.

Abstract

We transform superstring scattering amplitudes into the correlation functions of primary conformal fields on two-dimensional celestial sphere. The points on celestial sphere are associated to the asymptotic directions of (light-like) momenta of external particles, with the Lorentz group realized as the SL(2,C) conformal symmetry of the sphere. The energies are dualized through Mellin transforms into the parameters that determine dimensions of the primaries. We focus on four-point amplitudes involving gauge bosons and gravitons in type I open superstring theory and in closed heterotic superstring theory at the tree-level.