  A formulation of $\mathcal{N} = 2$ supersymmetric Yang-Mills theory with a
spacetime-dependent gauge coupling allows to study the breaking of conformal
symmetry at the quantum level. The theory has an energy-momentum tensor that is
only conserved if an equation of motion for the coupling is imposed. It admits
non-trivial solitons, among which the Wu-Yang monopole that can be regularized
and turns out to be massless. On the other hand, the ordinary BPS monopole is
only a solution in the large $N_c$ limit.
