Classification of non-Fermi liquids and their universal superconducting fluctuations: Part II

As a continuation of Part I, this talk will discuss concrete examples of non-Fermi liquids and their universal superconducting fluctuations. We use the dimensional regularization scheme to have controlled access to the interacting theories in two space dimensions. Due to the incoherence of fermions and the lack of scale invariance caused by Fermi momentum, the Fermi surface coupled with the U(1) gauge field is stable against pairing instability, although the universal pairing interactions are attractive in non-zero angular momentum channels. In contrast, the Ising-nematic quantum critical metal inevitably becomes a superconductor at low temperatures. Finally, we predict that in a non-Fermi liquid that exhibits universal pairing instability in a non-s-wave channel, there is a rather robust relation between T_c and the Fermi momentum.