Supersymmetric waves in Bose-Fermi mixtures

TL;DR

This paper explores how explicit symmetry-breaking perturbations affect the fermionic Goldstone mode in Bose-Fermi mixtures, revealing that such perturbations induce an energy gap and cause non-analytic behavior in thermodynamic pressure.

Contribution

It provides a detailed analysis of the impact of explicit symmetry breaking on the fermionic Goldstone mode in Bose-Fermi mixtures, a novel aspect in this field.

Findings

Goldstone mode acquires an energy gap when symmetry is explicitly broken.

Explicit symmetry-breaking leads to non-analyticity in thermodynamic pressure.

Fermionic Goldstone mode exhibits quadratic dispersion in the symmetric case.

Abstract

Interacting Bose-Fermi mixtures possess a fermionic (super)symmetry when bosons and fermions in the mixture have equal masses, and when the interaction strengths are appropriately tuned. This symmetry is spontaneously broken in the ground state of the mixture, leading to a novel Goldstone mode with fermionic statistics and quadratic dispersion. Here we examine the effect of explicit symmetry-breaking perturbations on the Goldstone mode. When the symmetry is not exact and the system is allowed to deviate from the symmetric point, we find that the Goldstone mode acquires an energy gap. We show that the excitations manifest themselves as a non-analyticity of the thermodynamic pressure.