Nonperturbative many-body physics in the open bosonic string

Abstract

We use covariant string field theory to explore many-body string physics. A candidate nonperturbative vacuum is identified via a level-truncation scheme. The breaking of internal and Lorentz symmetries is investigated. We show that tree-level string physics exhibits similarities to loop-level particle physics. The effective string coupling runs at tree level, inducing asymptotic freedom. This is a feature of any string theory. The running coupling has significant effects on the spectrum in the nonperturbative vacuum, including the disappearance of states.