arXiv:cond-mat/9607164 · Modern Physics Letters B
EFFECTIVE FIELD THEORY OF IDEAL-FLUID HYDRODYNAMICS
Adriaan M. J. Schakel
Abstract
Starting from a standard description of an ideal, isentropic fluid, we derive the effective theory governing a gapless non-relativistic mode — the sound mode. The theory, which is dictated by the requirement of Galilei invariance, entails the entire set of hydrodynamic equations. The gaplessness of the sound mode is explained by identifying it as the Goldstone mode associated with the spontaneous breakdown of Galilei invariance. Differences with a superfluid are pointed out.