Some all-order classical solutions in non-polynomial closed string field theory

Abstract

If a conformal field theory is perturbed by a nearly marginal operator of dimension (1 h, 1 h), then, under certain conditions and for a certain value of the perturbing parameter, we get a new conformal field theory. Starting from a string field theory based on the original conformal field theory, we show how to construct a classical solution in this string field theory to all orders in h, which represents string field theory formulated around the perturbed conformal field theory. We also show that the equation of motion of string field theory forces us to have a time-dependent dilaton background of the form ax⁰ to order h³, which compensates for the change in the central charge of the conformal field theory under the perturbation.