Collective physics in the closed bosonic string

Abstract

A second-quantized analysis is performed to examine many-body phenomena in closed bosonic strings. The covariant nonpolynomial closed-string field theory is developed in terms of particle fields and shown to contain interactions triggering a nonperturbative condensation of the tachyon field. We study the possibility that the higher-dimensional Lorentz symmetry spontaneously breaks. We show that the theory has asymptotic freedom due to a tree-level running coupling. The spectrum of states in the nonperturbative ground state is radically changed relative to the free casein particular, there is no massless graviton. Similar effects are anticipated in any nonperturbative vacuum.