Non-Fermi-Liquid Fixed Point for an Imbalanced Gas of Fermions in \$$1+\epsilon\$$ Dimensions

A. J. A. James and A. Lamacraft 2010. Physical Review Letters

# Abstract

We consider a gas of two species of fermions with population imbalance. Using the renormalization group in $$d=1+\epsilon$$ spatial dimensions, we show that for spinless fermions and $$2>\epsilon>0$$ a fixed point appears at finite attractive coupling where the quasiparticle residue vanishes, and identify this with the transition to Larkin-Ovchinnikov-Fulde-Ferrell order (inhomogeneous superconductivity). When the two species of fermions also carry spin degrees of freedom we find a fixed point indicating a transition to spin density wave order.