Phonon Bose-Einstein condensation in a Hubbard-phonon interacting system with infrared divergence

Abstract

We show that a finite Hubbard-phonon interacting system exhibits phonon BEC at sufficiently low temperature. We also have the gauge symmetry breaking for phonons. The key tools are a unitary transformation introduced by Arai and Hirokawa \protect{\cite{AH1}} and the Araki-Woods representation. This system is essentially the same as a free system or the van Hove model.

References in corpus (2)

• The ground state of a general electron-phonon Hamiltonian is a spin singlet
• Magnetism and infrared divergence in a Hubbard-phonon interacting system