SU(2) Yang-Mills theory with extended supersymmetry in a background magnetic field - art. no. 105010

The vacuum structure of N = 2 (and N = 4) supersymmetric Yang-Mills theory is analyzed in detail by considering the effective potential for constant b ackground scalar-magnetic fields within different approximations. We compar e the one-loop approximation with or without instanton improved effective c oupling with the one-loop result in the dual description. For N = 2 we find that non-perturbative monopole degrees of freedom remove the non-trivial m inima present in the (improved) one-loop potential in the strong-coupling r egime. The combination of Yang-Mills theory and the dual description leads to a self-consistent effective potential over the full range of background fields. [S0556-2821(99)01208-4].