Worldsheet scattering for the GKP string

TL;DR

This paper studies the scattering matrix of excitations on the GKP string at strong coupling, using string theory and integrability techniques to compute and verify S-matrix elements and their factorization.

Contribution

It provides the first perturbative calculation of the GKP string S-matrix at strong coupling and confirms integrability constraints through explicit checks.

Findings

Tree-level S-matrix elements match Bethe Ansatz predictions

Three-body S-matrix factorization is confirmed

Results support integrability of the GKP string system

Abstract

We initiate the perturbative study of the S-matrix for the excitations on top of the GKP vacuum at strong coupling. Using the string sigma model action expanded around the null cusp classical solution, we compute the tree-level S-matrix elements and compare them with the predictions from the asymptotic Bethe Ansatz. We also check the factorization of the three-body S-matrix for various bosonic processes, finding precise agreement with the constraints imposed by integrability.