Super Efimov effect of resonantly interacting fermions in two dimensions
Sergej Moroz, Yusuke Nishida, and Dam Thanh Son
Accepted
We study a system of spinless fermions in two dimensions with a short-range interaction fine-tuned to a p-wave resonance. We show that three such fermions form an infinite tower of bound states of orbital angular momentum l = 1 and their binding energies obey a universal doubly exponential scaling, E3(n) exp(-2e3pn/4+q), at large n. This "super Efimov effect" is found by a renormalization group analysis and confirmed by solving the bound state problem. We also provide an indication that there are l = 2 four-body resonances associated with every three-body bound state at E4(n) exp(-2e3pn/4+q-0.188). These universal few-body states may be observed in ultracold atom experiments and should be taken into account in future many-body studies of the system.