3,726 research outputs found
General Formulation for Proton Decay Rate in Minimal Supersymmetric SO(10) GUT
We make an explicit formulation for the proton decay rate in the minimal
renormalizable supersymmetric (SUSY) SO(10) model. In this model, the Higgs
fields consist of and SO(10) representations in
the Yukawa interactions with matter and of , , , and representations in the Higgs potential. We present all
the mass matrices for the Higgs fields contained in this minimal SUSY SO(10)
model. Finally, we discuss the threshold effects of these Higgs fields on the
gauge coupling unification.Comment: 32 pages, typos are corrected, a few references and comments to the
papers arXiv:hep-ph/0204097 and arXiv:hep-ph/0402122 are adde
Condition for the Existence of Complex Modes in a Trapped Bose--Einstein Condensate with a Highly Quantized Vortex
We consider a trapped Bose--Einstein condensate (BEC) with a highly quantized
vortex. For the BEC with a doubly, triply or quadruply quantized vortex, the
numerical calculations have shown that the Bogoliubov--de Gennes equations,
which describe the fluctuation of the condensate, have complex eigenvalues. In
this paper, we obtain the analytic expression of the condition for the
existence of complex modes, using the method developed by Rossignoli and
Kowalski [R. Rossignoli and A. M. Kowalski, Phys. Rev. A 72, 032101 (2005)] for
the small coupling constant. To derive it, we make the two-mode approximation.
With the derived analytic formula, we can identify the quantum number of the
complex modes for each winding number of the vortex. Our result is consistent
with those obtained by the numerical calculation in the case that the winding
number is two, three or four. We prove that the complex modes always exist when
the condensate has a highly quantized vortex
CP Violations in Lepton Number Violation Processes and Neutrino Oscillations
We examine the constraints on the MNS lepton mixing matrix from the present
and future experimental data of the neutrino oscillation and lepton number
violation processes. We introduce a graphical representation of the CP
violation phases which appear in the lepton number violation processes such as
neutrinoless double beta decay, the conversion, and the K decay,
Using this graphical representation, we derive the
constraints on the CP violation phases in the lepton sector.Comment: 21pp, REVTeX, 9 Figure
Quantum Spin Hall Effect and Enhanced Magnetic Response by Spin-Orbit Coupling
We show that the spin Hall conductivity in insulators is related with a
magnetic susceptibility representing the strength of the spin-orbit coupling.
We use this relationship as a guiding principle to search real materials
showing quantum spin Hall effect. As a result, we theoretically predict that
bismuth will show the quantum spin Hall effect, both by calculating the helical
edge states, and by showing the non-triviality of the Z_2 topological number,
and propose possible experiments.Comment: 5 pages, 2 figures, accepted for publication in Phys. Rev. Let
Signature of stripe pinning in optical conductivity
The response of charge stripes to an external electric field applied
perpendicular to the stripe direction is studied within a diagrammatic approach
for both weak and strong pinning by random impurities. The sound-like mode of
the stripes described as elastic strings moves to finite frequency due to
impurity pinning. By calculating the optical conductivity we determine this
characteristic energy scale for both a single stripe and an array of
interacting stripes. The results explain the anomalous far-infrared peak
observed recently in optical-conductivity measurements on cuprates.Comment: Revised version, to appear in Phys. Rev.
What Does mu-tau Symmetry Imply about Neutrino Mixings?
The requirement of the mu-tau symmetry in the neutrino sector that yields the
maximal atmospheric neutrino mixing is shown to yield either sin(\theta_{13})=0
(referred to as C1)) or sin(\theta_{12})=0 (referred to as C2)), where
\theta_{12(13)} stands for the solar (reactor) neutrino mixing angle. We study
general properties possessed by approximately mu-tau symmetric textures. It is
argued that the tiny mu-tau symmetry breaking generally leads to
cos(2\theta_{23}) \simsin(\theta_{13}) for C1) and cos(2\theta_{23}) \sim
\Delta m^2_\odot/\Delta m^2_{atm}(\equiv R) for C2), which indicates that the
smallness of cos(2\theta_{23}) is a good measure of the mu-tau symmetry
breaking, where \Delta m^2_{atm} (\Delta m^2_\odot) stands for the square mass
differences of atmospheric (solar) neutrinos. We further find that the relation
R \sim sin^2(\theta_{13}) arises from contributions of O(sin^2(\theta_{13})) in
the estimation of the neutrino masses (m_{1,2,3}) for C1), and that possible
forms of textures are strongly restricted to realize sin^2(2\theta_{12})=O(1)
for C2). To satisfy R \sim sin^2(\theta_{13}) for C1), neutrinos exhibit the
inverted mass hierarchy, or the quasi degenerate mass pattern with | m_{1,2,3}|
\sim O(\sqrt{\Delta m^2_{atm}}), and, to realize sin^2(2\theta_{12})=O(1) for
C2), there should be an additional small parameter \eta whose size is
comparable to that of the mu-tau symmetry breaking parameter \epsilon, giving
tan(2\theta_{12}) \sim \epsilon/\eta with \eta \sim \epsilon to be compatible
with the observed large mixing.Comment: 10 pages, title slightly modified, comments added in the introdction,
typos corrected, references updated, version to appear in Physical Reviews
Theoretical Study of Friction: A Case of One-Dimensional Clean Surfaces
A new method has been proposed to evaluate the frictional force in the
stationary state. This method is applied to the 1-dimensional model of clean
surfaces. The kinetic frictional force is seen to depend on velocity in
general, but the dependence becomes weaker as the maximum static frictional
force increases and in the limiting case the kinetic friction gets only weakly
dependent on velocity as described by one of the laws of friction. It is also
shown that there is a phase transition between state with vanishing maximum
static frictional force and that with finite one. The role of randomness at the
interface and the relation to the impurity pinning of the sliding
Charge-Density-Wave are discussed. to appear in Phys.Rev.B. abstract only. Full
text is available upon request. E-mail: [email protected]: 2 pages, Plain TEX, OUCMT-94-
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