Transport Equation for Nambu-Goto Strings
We consider a covariant approach to coarse-graining a network of interacting NambuGoto strings. A transport equation is constructed for a spatially at Friedmann universe. In Minkowski space and with no spatial dependence this model agrees with a previous model. Thus it likewise converges to an equilibrium with a factorizability property. We present an argument that this property does not depend on a ‘string chaos’ assumption on the correlations between strings. And in contrast to the earlier model, this transport equation agrees with conservation equations for a uid of strings derived from a dierent perspective.