Effective String Theory in a Tank

Abstract

In this talk, the speaker will discuss the effective string theory of vortex lines in low-temperature superfluids and ordinary fluids. After briefly reviewing the effective theory of phonons in superfluids, he will derive the most general low-energy effective Lagrangian for vortex lines that is compatible with (spontaneously broken) Poincaré invariance and worldsheet reparameterization invariance. By applying standard field-theoretical techniques, he will show that certain low-energy coupling constants (most notably the string tension) exhibit RG running already at the classical level. This insight does not only shed a new light on well-known properties of vortex lines (e.g. the unconventional dispersion relation of the Kelvin waves), but also allows to derive some new results. As an illustration, he will discuss how this formalism can be applied to study large-amplitude Kelvin waves and absorption of bulk phonons by a vortex line.