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CFT Zoo

Banks-Zaks fixed point

A Banks-Zaks fixed point is an IR-stable CFT describing long-distance behavior of QCD for certain parameters. The Lagrangian of QCD is L=aˉψa(iγma)ψa14F2 where color and spacetime indices have been suppressed. The flavor index a runs over Nf flavors of fermions.

This theory is asymptotically free (i.e., has a UV-stable fixed point) for Nf<332. For Nf just below that threshold, an IR-stable fixed point is visible in perturbation theory if the fermions are taken to be massless. This fixed point has been found to extend down at least to Nf12 in lattice studies.

Other theories can have Banks-Zaks fixed points, like SQCD.

Lattice studies