1996/09/25 by H. Leutwyler · 3 citations
Physics and Astronomy · #hep-ph
published as Helv.Phys.Acta 70 (1997) 275-286 · 12 pages, Latex file
arxiv created 1996/09/25 · arxiv updated 2009/11/30
The implications of the hidden, spontaneously broken symmetry for the properties of the sound waves of a solid are analyzed. Although the discussion does not go beyond standard wisdom, it presents some of the known results from a different perspective. In particular, I argue that, as a consequence of the hidden symmetry, the equations of motion for a sound wave necessarily contain nonlinear terms, describing phonon-phonon scattering and emphasize the analogy with the low energy theorems for pion-pion scattering.