Supersymmetric U(N) Gauge Model and Partial Breaking of N=2 Supersymmetry

We review the construction of the N=2 U(N) gauge model and the analysis of vacua of the model. On the vacua, N=2 supersymmetry is spontaneously broken to N=1, and the gauge symmetry is broken to a product gauge group \prod_{i=1}^n U(N_i). The masses of the supermultiplets appearing on the N=1 vacua are given. We provide a manifestly N=2 supersymmetric formulation of the U(N) gauge model coupled with N=2 hypermultiplets, and show that N=2 supersymmetry is partially broken down to N=1 spontaneously.