R-Parity violation in a SUSY GUT model and radiative neutrino masses

[出版社版]Within the framework of an SU(5) SUSY GUT model, a mechanism which effectively induces R-parity-violating terms below the unification energy scale MX is proposed. The model has matter fields 5^^-_<L(+)> + 10_<L(-)> and Higgs fields H_<(-)> and H^^-_<(+)> in addition to the ordinary Higgs fields H_<(+)> and H^^-_<(-)> which contribute to the Yukawa interactions, where (±) denote the transformation properties under a discrete symmetry Z_2. The Z_2 symmetry is only broken by the μ-term H^^-_<(+)>H_<(-)> softly, so that the 5^^-_<(+)> ↔? H^^-_<(+)> ↔ H^^-_<(-)> mixing appears at μ < mSB, and R-parity violating terms 5^^-_L5^^-_L10_L are effectively induced from the Yukawa interactions H^^-_<(-)>5^^-_<L(+)>10_<L(-)>, i.e. the effective coupling constants λ_<ijk> of ν_<Li>e_<LJ>e^c_<Rk> and ν_<Li>d^c_<Rj>d_<Lk> are proportional to the mass matrices (M_e)_<jk> and (M_d)_<jk>, respectively. The parameter regions which are harmless for the proton decay are investigated. Possible forms of the radiatively induced neutrino mass matrix are also investigated