Fluid Mechanics of Strings

TL;DR

This paper develops a formal framework for analyzing the fluid-like behavior of networks of one-dimensional strings, including cosmic strings, by deriving hydrodynamic equations from conserved currents and coarse-graining procedures.

Contribution

It introduces a systematic coarse-graining method for string networks and derives comprehensive hydrodynamic equations for strings described by the Nambu-Goto action.

Findings

Established a formal procedure for coarse-graining string networks.

Derived hydrodynamic equations incorporating energy-momentum and tangent vector currents.

Applied the framework specifically to cosmic strings modeled by the Nambu-Goto action.

Abstract

We consider conserved currents in an interacting network of one-dimensional objects (or strings). Singular currents localized on a single string are considered in general, and a formal procedure for coarse-graining over many strings is developed. This procedure is applied to strings described by the Nambu-Goto action such as cosmic strings. In addition to conserved currents corresponding to the energy-momentum tensor, we consider an antisymmetric tensor of conserved currents related to the string tangent vector. Under the assumption of local equilibrium we derive a complete set of hydrodynamic equations for strings.