Harmonic superspace with four-dimensional Euclidean space

The supersymmetry algebra in four-dimensional Euclidean space is formulated in such a way that an SU(2) invariance of the algebra is apparent. This leads to a superfield formalism for representations of the algebra that can be adapted to harmonic superspace. Models in this harmonic superspace are quite similar to N = 2 models in four-dimensional Minkowski space.