Effective Free Energy of Ginzburg-Landau Model

It is argued that the presence of a nonanalytic term in the effective potential of the Ginzburg-Landau model is immaterial as far as the order of the superconductor-normal phase transition is concerned. To achieve agreement with the renormalization group, the effective potential has to be extended to include derivative terms, which provide the theory with a low momentum scale which can be varied to probe the (possible) fixed point.Comment: 6 pages, contribution to the Festschrift dedicated to Professor Kleinert on the occasion of his 60th birthda

Effective Field Theory of ideal-fluid Hydrodynamics

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.Comment: 17 pages, REVTe