Stability of SU(Nc) QCD3 from the ε-expansion

QCD with gauge group SU(N-c) flows to an interacting conformal fixed point in three spacetime dimensions when the number of four-component Dirac fermions N-f >> N-c. We study the perturbative stability of this fixed point via the.-expansion about four dimensions. We find that when the number of fermions is lowered to N-f(crit) approximate to 11/2 N-c + (6 + 4/N-c)epsilon, a certain four-fermion operator becomes relevant and the theory flows to a new infrared fixed point that may be either massless or massive. F-theorem or entanglement monotonicity considerations complement our epsilon-expansion calculation.