2,800 research outputs found
Large Lepton Mixing in a Coset-space Family Unification on
We study a coset-space unification model for families based on . We find that qualitative structure of quark and lepton mass
matrices in this model describes very well the observation. We stress, in
particular, that the large mixing angle, , required for the atmospheric neutrino oscillation reported by the
SuperKamiokande collaboration, is naturally obtained, which is a consequence of
unparallel family structure in the present coset-space unification.Comment: 8 pages, Latex2
A Solution to the Polonyi Problem in the Minimum SUSY-GUT
We show that the Polonyi problem is solved in the minimum SUSY-GUT model in
which a self-coupling strength for a heavy Higgs , ,
is very small . It is stressed that with this small
the mass of the physical becomes m_{\Sigma} \sim
10^{12}\GEV and the unification scale is raised up to the gravitational one,
M\simeq 2\times 10^{18}\GEV. A potential problem, however, is also pointed
out in this GUT model
Higher Dimensional Supersymmetry as an Origin of the Three Families for Quarks and Leptons
In a (0,1) supersymmetric (SUSY) six-dimensional gauge theory, a gauge
fermion gives rise to box anomalies. These anomalies are completely canceled by
assuming a vector multiplet of (1,1) SUSY. With a T^2/Z_3 orbifold
compactification of the extra two dimensional space, the theory provides three
chiral multiplets and three equivalent fixed points. We regard them as the
origin of the three families of quarks and leptons. Quasi anarchy structure in
the SU(5)-5^* representation sector and hence the bimaximal mixing in the
neutrino oscillation are explained quite naturally in this framework. We also
discuss a family symmetry as a remnant of the higher-dimensional R symmetry.Comment: 12 pages, Contribution to "Peccei Fest" January 11-13,2002, a number
of comments and an appendix are adde
Geometric Origin of Large Lepton Mixing in a Higher Dimensional Spacetime
The large mixing in the lepton sector observed in the recent
neutrino-oscillation experiments strongly suggest that nature of left-handed
lepton doublets is very different from that of left-handed quark doublets. This
means that there is a big disparity between the matter multiplets 5^*'s and
10's in the SU(5) unified theory. We show that this big difference can be
explained in a six-dimensional spacetime compactified on the T^2/Z_3 orbifold.
That is, we propose to put three families of 5^*'s on three equivalent fixed
points of the orbifold and the three 10's in the two-dimensional bulk. We
construct an explicit model realizing this situation and show that the
democratic mass structure in the lepton sector is naturally obtained and hence
the model explains the observed bi-large lepton mixing and simultaneously the
required small mixing U_e3. The mass matrices and mixing in the quark sector
are also briefly discussed.Comment: 12 pages, including 1 figure and 1 table, one paragraph and two
references adde
Quark Lepton Mass Hierarchies and the Baryon Asymmetry
The mass hierarchies of quarks and charged leptons as well as a large
\n_\m-\n_\t mixing angle are naturally explained by the Frogatt-Nielsen
mechanism with a nonparallel family structure of chiral charges. We extend this
mechanism to right-handed neutrinos. Their out-of-equilibrium decay generates a
cosmological baryon asymmetry whose size is quantized in powers of the
hierarchy parameter \e^2. For the simplest hierarchy pattern the neutrino
mass \bar{m}_\n= (m_{\n_\m}m_{\n_\t})^{1/2} \sim 10^{-2} eV, which is
inferred from present indications for neutrino oscillations, implies a baryon
asymmetry . The corresponding baryogenesis temperature is
GeV.Comment: 7 page
An N=2 SUSY Gauge Model for Dynamical Breaking of the Grand Unified SU(5) Symmetry
We construct an extension of the recently proposed dynamical model for the
breaking of SU(5) gauge symmetry, in which a pair of massless
chiral supermultiplets for Higgs doublets are naturally obtained. We point out
that a model at a specific point in the parameter space of superpotential is
regarded as a low-energy effective theory of an N=2 supersymmetric gauge model
for the strongly interacting hypercolor sector.Comment: 7 page
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