Alternative low energy supersymmetry

This paper reports on models of low energy supersymmetry which require some additional symmetry beyond the known gauge symmetries. The usual preference for R parity, which leads to the standard low energy supersymmetry model, has no clear theoretical motivation. The alternative models with minimal field content are reviewed. In one case R parity is spontaneously broken by a large neutrino vev. In three other cases R parity is replaced by an alternative symmetry; baryon number, lepton number or ZN