Non-Abelian Duality and Confinement in N=2 Supersymmetric QCD

Understand

In N=2 supersymmetric QCD with the U(N) gauge group and N_f>N we study the crossover transition from the weak coupling regime at large \xi to strong coupling at small \xi where \xi is the Fayet--Iliopoulos parameter.

• We find that at strong coupling a dual non-Abelian weakly coupled N=2 theory exists which describes low-energy physics at small \xi.
• The dual gauge group is U(N_f-N) and the dual theory has N_f flavors of light dyons, to be compared with N_f quarks in the original U(N) theory.
• Both, the original and dual theories are Higgsed and share the same global symmetry SU(N) x SU(N_f-N) x U(1), albeit the physical meaning of the SU(N) and SU(N_f-N) factors is different in the large- and small-\xi regimes.