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

Understand

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.