Minimal residual entropy in (0+1)-dimensional non-Fermi liquids

In the large N limit a physical system might acquire a residual entropy at zero temperature even without ground-state degeneracy. At the same time poles in the two-point function might coalesce and form a branch cut. Both phenomena are related to a high density of states in the large N limit. In this paper we address the following question: Does a branch cut in the two-point function always lead to nonzero residual entropy? We argue that for generic fermionic systems in 0 + 1 dimensions in the mean-field approximation the answer is positive: Branch cut 1/tau 2 ⠃ in the two-point function does lead to a lower bound N log 2(1/2 - ⠃) for the entropy. We also comment on higher-dimensional generalizations and relations to the holographic correspondence.

Automated summary

This paper investigates the relationship between residual entropy and branch cuts in the large N limit and concludes that for generic fermionic systems in the mean-field approximation, a branch cut in the two-point function does lead to a lower bound for the entropy.