Harmonic superspace: key to N = 2 supersymmetry theories
Gal'perin A. , Ivanov E. , Ogievetskii V., Sokachev E.
The concept of a harmonic N = 2 superspace with additional coordinates related to the SU(2)/U(1) sphere is introduced. This concept leads to an adequate geometric description of the N = 2 theories of matter, the Yang-Mills theory, and supergravity in terms of superfields without coupling. A new effect has been discovered: the unboundedness of the number of gauge and auxiliary degrees of freedom.