https://doi.org/10.1140/epjc/s10052-019-7498-5
Regular Article - Theoretical Physics
Simplest phonons and pseudo-phonons in field theory
1
Universidad de Santiago de Compostela (USC), Santiago de Compostela, Spain
2
Instituto Galego de Física de Altas Enerxías (IGFAE), Santiago de Compostela, Spain
* e-mail: daniele.musso@usc.es
Received:
23
February
2019
Accepted:
19
November
2019
Published online:
4
December
2019
We study the emergence of Nambu–Goldstone modes due to broken translation symmetry in field theory. Purely spontaneous breaking yields a massless phonon which develops a mass upon introducing a perturbative explicit breaking. The pseudo-phonon mass agrees with Gell Mann-Oakes-Renner relations. We analyze the simplest possible theories featuring gradient Mexican hats and describing space-dependent order parameters. We comment on homogeneous translation breaking and the connections with holographic Q-lattices.
© The Author(s), 2019
