On vacuum structures of N=2 LSUSY QED equivalent to N=2 NLSUSY model

The vacuum structure of N=2 linear supersymmetry (LSUSY) invariant QED, which is equivalent to N=2 nonlinear supersymmetry (NLSUSY) model, is studied explicitly in two-dimensional space-time (d=2). Two different isometries SO(1,3) and SO(3,1) appear for the vacuum field configuration corresponding to the various parameter regions. Two different field configurations of SO(3,1) isometry describe the two different physical vacua, i.e. one breaks spontaneously both U(1) and SUSY and the other breaks spontaneously SUSY alone.