674 research outputs found
R-Parity Violation and Family Symmetry
In this talk, we investigate the implications of R-parity violating (RPV)
operators in a model with family symmetry. Family symmetry can determine the
form of RPV operators as well as the Yukawa matrices. We consider a concrete
model with non-abelian discrete symmetry Q_6, which has only three RPV
trilinear operators with no baryon number violating terms. We find that ratios
of decay rates of the lepton flavor violating processes are fixed thanks to the
family symmetry, predicting BR(tau to 3e)/BR(tau to 3mu) ~ 4
m_{mu}^2/m_{tau}^2.Comment: 11pages, 2 figures. Talk given at CTP symposium on Supersymmetry at
LHC: Theoretical and Experimental Perspectives, The British University in
Egypt, Cairo, Egypt, 11-14 March 200
Common origin of \theta_{13} and \Delta m^2_{12} in a model of neutrino mass with quaternion symmetry
The smallness of the 1-3 lepton mixing angle and of the
neutrino mass-squared-difference ratio can be
understood as the departure from a common limit where they both vanish. We
discuss in general the conditions for realizing the mass degeneracy of a pair
of neutrinos and show that the vanishing of a CP violating phase is needed. We
find that the discrete quaternion group Q of eight elements is the simplest
family symmetry which correlates the smallness of to the
value of . In such a model we predict if the ordering of the neutrino mass spectrum is
normal, and if it is inverted.Comment: revtex, 7 pages, 6 pdf figures; Appendix added discussing in detail
the alignment of VEV
Gauged Discrete Symmetries and Proton Stability
We discuss the results of a search for anomaly free Abelian Z_N discrete
symmetries that lead to automatic R-parity conservation and prevents dangerous
higher-dimensional proton decay operators in simple extensions of the minimal
supersymmetric extension of the standard model (MSSM) based on the left-right
symmetric group, the Pati-Salam group and SO(10). We require that the
superpotential for the models have enough structures to be able to give correct
symmetry breaking to MSSM and potentially realistic fermion masses. We find
viable models in each of the extensions and for all the cases, anomaly freedom
of the discrete symmetry restricts the number of generations.Comment: 8 pages, 2 figures; v2 : typos fixed, references adde
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Large superconducting dipole magnet for the heavy ion spectrometer system (HISS)
The magnet is the central element of the spectrometer system, where it will be used to momentum-analyze secondary heavy-ion fragments at relativistic energies. High bending power and large acceptance apertures are necessary for simultaneous multiple fragment measurements. Free access over large angles to the magnetic volume is necessary to accommodate a variety of experiments and particle detection systems. The magnet has pole tips two meters in diameter, a one meter gap, and a maximum central field of three tesla. The coils are designed to be cryostable, with a helical winding pattern. A window-frame steel yoke limits the stray field and augments the cental field. In terms of its magnetic energy of 55 MJ it will be one of the twelve or so largest magnets in the world. Unusual engineering features of the magnet are the large magnetic forces (one million kg) between the coils at liquid helium temperature and the yoke at room temperature, and the large diameter (7 m) hydraulic cylinder base to provide rotation for the magnet. The magnet will be installed at the BEVALAC heavy-ion facility at Lawrence Berkeley Laboratory
Non-Abelian Discrete Flavor Symmetries on Orbifolds
We study non-Abelian flavor symmetries on orbifolds, and .
Our extra dimensional models realize , , and
including and . In addition, one can also realize
their subgroups such as , , etc. The flavor symmetry can be
realized on both and orbifolds.Comment: 16 page
Bilinear R-parity violation with flavor symmetry
Bilinear R-parity violation (BRPV) provides the simplest intrinsically
supersymmetric neutrino mass generation scheme. While neutrino mixing
parameters can be probed in high energy accelerators, they are unfortunately
not predicted by the theory. Here we propose a model based on the discrete
flavor symmetry with a single R-parity violating parameter, leading to
(i) correct Cabbibo mixing given by the Gatto-Sartori-Tonin formula, and a
successful unification-like b-tau mass relation, and (ii) a correlation between
the lepton mixing angles and in agreement with
recent neutrino oscillation data, as well as a (nearly) massless neutrino,
leading to absence of neutrinoless double beta decay.Comment: 16 pages, 3 figures. Extended version, as published in JHE
Direct and Indirect Detection of Dark Matter in D6 Flavor Symmetric Model
We study a fermionic dark matter in a non-supersymmetric extension of the
standard model with a family symmetry based on D6xZ2xZ2. In our model, the
final state of the dark matter annihilation is determined to be e+ e- by the
flavor symmetry, which is consistent with the PAMELA result. At first, we show
that our dark matter mass should be within the range of 230 GeV - 750 GeV in
the WMAP analysis combined with mu to e gamma constraint. Moreover we
simultaneously explain the experiments of direct and indirect detection, by
simply adding a gauge and D6 singlet real scalar field. In the direct detection
experiments, we show that the lighter dark matter mass ~ 230 GeV and the
lighter standard model Higgs boson ~ 115 GeV is in favor of the observed bounds
reported by CDMS II and XENON100. In the indirect detection experiments, we
explain the positron excess reported by PAMELA through the Breit-Wigner
enhancement mechanism. We also show that our model is consistent with no
antiproton excess suggested by PAMELA.Comment: 20 pages, 9 figures, 2 tables, accepted version for publication in
European Physical Journal
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