Low energy physics of interacting bosons with a moat spectrum, and the implications for condensed matter and cold nuclear matter

TL;DR

This paper explores the unique low-energy behaviors of bosonic systems with a moat spectrum, revealing phase transitions and implications for condensed matter and nuclear physics, including transport properties and non-Fermi liquid states.

Contribution

It analyzes the effects of a moat spectrum on bosonic models with different symmetries and discusses their implications for condensed matter and nuclear matter, highlighting new phase transition phenomena.

Findings

For N=2, two phase transitions occur: Bose condensation at zero temperature and spatially inhomogeneous states at finite temperature.

For N>2, a mass gap is generated dynamically at any temperature, altering low-energy excitations.

Moat spectra influence transport properties and may lead to non-Fermi liquid behavior in nuclear matter.

Abstract

We discuss bosonic models with a moat spectrum, where in momentum space the minimum of the dispersion relation is on a sphere of nonzero radius. For spinless bosons with $O(N)$ symmetry, we emphasize the essential difference between $N=2$ and $N > 2$. When $N=2$, there are two phase transitions: at zero temperature, a transition to a state with Bose condensation, and at nonzero temperature, a transition to a spatially inhomogeneous state. When $N > 2$, previous analysis suggests that a mass gap is generated dynamically at any temperature. In condensed matter, a moat spectrum is important for spin-orbit-coupled bosons. For cold nuclear or quarkyonic matter, we suggest that the transport properties, such as neutrino emission, are dominated by the phonons related to a moat spectrum; also, that at least in the quarkyonic phase the nucleons may be a non-Fermi liquid.