Superembeddings, Partial Supersymmetry Breaking and Superbranes

It is advocated that the superembedding approach is a generic covariant method for the description of superbranes as models of (partial) spontaneous supersymmetry breaking. As an illustration we construct (in the framework of superembeddings) an n=1, d=3 worldvolume superfield action for a supermembrane propagating in N=1, D=4,5,7 and 11-dimensional supergravity backgrounds. We then show how in the case of an N=1, D=4 target superspace gauge fixing local worldvolume superdiffeomorphisms in the covariant supermembrane action results in an effective N=2, d=3 supersymmetric field theory with N=2 supersymmetry being spontaneously broken down to N=1. The broken part of N=2, d=3 supersymmetry is nonlinearly realized when acting on Goldstone N=1, d=3 superfields, which describe physical degrees of freedom of the model. As an introduction to the formalism, the procedure of getting effective field theories with partially broken supersymmetry by gauge fixing covariant superbrane actions is also demonstrated with a simpler example of a massive N=2, D=2 superparticle.