An effective field theory for acoustic and pseudo-acoustic phonons in solids

Abstract: Solids generally feature many phonon branches, with different dispersion relations. Gapless acoustic phonons are known to be the Goldstone bosons of the spontaneous breaking of spacetime symmetries associated to the solid phase. Other gapped phonons are generally non-universal degrees of freedom, which depend on the microscopic details of the solid. In this talk I will show that some of these gapped phonons can actually be seen as pseudo-Goldstones associated to some small explicit breaking. In this regime it is possible to include them in a low-energy EFT, together with the gapless phonons. I will explicitly construct such an EFT for the case of one and two spatial dimensions, two ‘flavors’ and in the isotropic limit. I will then compute some test observables and show that they match what already known (when available).

cosmology and nongalactic astrophysicsother condensed matterquantum gasesstrongly correlated electronssuperconductivitygeneral relativity and quantum cosmologyHEP - theory

Audience: researchers in the topic

Carnegie Mellon theoretical physics