English

Soft Phonon Theorems

High Energy Physics - Theory 2024-05-13 v2 Other Condensed Matter High Energy Physics - Phenomenology

Abstract

A variety of condensed matter systems describe gapless modes that can be interpreted as Nambu-Goldstone bosons of spontaneously broken Poincar\'e symmetry. In this paper we derive new soft theorems constraining the tree-level scattering of these degrees of freedom, as exhibited in solids, fluids, superfluids, and framids. These soft theorems are in one-to-one correspondence with various broken symmetries, including spacetime translations, Lorentz boosts, and, for the case of fluids, volume-preserving diffeomorphisms. We also implement a bootstrap in which the enhanced vanishing of amplitudes in the soft limit is taken as an input, thus sculpting out a subclass of exceptional solid, fluid, and framid theories.

Keywords

Cite

@article{arxiv.2301.11363,
  title  = {Soft Phonon Theorems},
  author = {Clifford Cheung and Maria Derda and Andreas Helset and Julio Parra-Martinez},
  journal= {arXiv preprint arXiv:2301.11363},
  year   = {2024}
}

Comments

35 pages

R2 v1 2026-06-28T08:22:17.341Z