Branes and Theta Dependence

TL;DR

This paper investigates the $ heta$ dependence of four-dimensional $SU(N_c)$ super Yang-Mills and super QCD using M theory fivebranes, calculating vacuum energy and string tension in a supergravity approximation, aligning with field theory expectations.

Contribution

It introduces a novel approach using M theory fivebranes to analyze $ heta$ dependence in supersymmetric gauge theories, providing qualitative agreement with field theory results.

Findings

Vacuum energy computed matches qualitative field theory predictions.

QCD string tension's $ heta$ dependence studied via fivebrane.

Results support supergravity approximation validity.

Abstract

We use the fivebrane of M theory to study the $\theta$ dependence of four dimensional $SU(N_c)$ super Yang-Mills and super QCD softly broken by a gaugino mass. We compute the energy of the vacuum in the supergravity approximation. The results obtained are in qualitative agreement with field theory. We also study the $\theta$ dependence of the QCD string tension via the fivebrane.