429 research outputs found

### CP and T violation in long baseline experiments with low energy neutrino

Stimulated by the idea of PRISM, a very high intensity muon ring with rather
low energy, we consider possibilities of observing CP-violation effects in
neutrino oscillation experiments. Destructive sum of matter effect and
CP-violation effect can be avoided with use of initial $\nu_{\rm e}$ beam. We
finally show that the experiment with (a few) $\times$ 100 MeV of neutrino
energy and (a few) $\times$ 100 km of baseline length, which is considered in
this paper, is particularly suitable for a search of CP violation in view of
3-generation nature of CP violation.Comment: 8 pages, 1 figure. To be published in the proceedings of KEK
International Workshop on High Intensity Muon Sources (HIMUS 99), Tsukuba,
Japan, 1-4 Dec 199

### An SU(5) SUSY Model with R-Parity Violation and Radiatively Induced Neutrino Masses

The radiatively induced neutrino mass matrix is investigated on the basis of
an SU(5) SUSY model. In order to evade the proton decay, an ansatz based on a
discrete symmetry $Z_2$ is assumed: although, at the unification scale, we have
two types of superfields $\Psi_{L(\pm)}=\bar{5}_{L(\pm)}+10_{L(\pm)}$, which
are transformed as $\Psi_{L(\pm)} \to \pm \Psi_{L(\pm)}$ under the discrete
symmetry Z$_2$, the particles $\Psi_{L(+)}$ are decoupled after the SU(5)
symmetry is broken, so that our quarks and leptons belong to \Psi_{L(-)}. The
R-parity-violating terms for our quarks and leptons \Psi_{L(-)} are basically
forbidden under the symmetry Z_2. However, we assume that mixings between
members of \Psi_{L(+)} and those of \Psi_{L(-)} are in part caused after SU(5)
is broken. As a result, the R-parity-violating interactions are in part
allowed, so that the neutrino masses are radiatively generated, while the
proton decay due to the R-parity violating terms is still forbidden because the
term d_R^c d_R^c u_R^c has z=-1.Comment: 6 pages, Revtex, no figur

### Dynamical Symmetry Breaking in an E_6 GUT Model

Dynamical symmetry breaking is studied in an E_6 GUT model of a single
generation of fermions with strong 4-fermi interactions. The effective
potential is analyzed analytically by the help of Michel's conjecture and the
result is confirmed numerically. We find that the E_6 symmetry is spontaneously
broken either to F_4 or to Sp(8) or G_2 or SU(3), depending on which of the
4-fermi coupling constants G_27 and G_351 in the 27/351 channels is stronger.
The possibilities for obtaining other type of breaking patterns are also
discussed.Comment: 29 pages (no figures), phyzzx and tables.tex KUNS-125

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