String Interactions from Matrix String Theory

TL;DR

This paper calculates transition amplitudes in Matrix String Theory, showing they match expected string interaction factors, thus linking gauge theory solutions to string interactions.

Contribution

It provides the first detailed calculation of transition amplitudes around BPS solutions in Matrix String Theory, connecting gauge theory and string perturbation theory.

Findings

Amplitudes are proportional to g_s^{- ext{Euler characteristic}}

Results match perturbative string interaction expectations

Supports interpretation of Matrix String Theory as a string theory

Abstract

The Matrix String Theory, i.e. the two dimensional U(N) SYM with N=(8,8) supersymmetry, has classical BPS solutions that interpolate between an initial and a final string configuration via a bordered Riemann surface. The Matrix String Theory amplitudes around such a classical BPS background, in the strong Yang--Mills coupling, are therefore candidates to be interpreted in a stringy way as the transition amplitude between given initial and final string configurations. In this paper we calculate these amplitudes and show that the leading contribution is proportional to the factor g_s^{-\chi}, where \chi is the Euler characteristic of the interpolating Riemann surface and g_s is the string coupling. This is the factor one expects from perturbative string interaction theory.