8,700 research outputs found
Can the Lepton Flavor Mixing Matrix Be Symmetric?
Current neutrino oscillation data indicate that the 3x3 lepton flavor mixing
matrix V is likely to be symmetric about its V_{e3}-V_{\mu 2}-V_{\tau 1} axis.
This off-diagonal symmetry corresponds to three pairs of {\it congruent}
unitarity triangles in the complex plane. Terrestrial matter effects can
substantially modify the genuine CP-violating parameter and off-diagonal
asymmetries of V in realistic long-baseline experiments of neutrino
oscillations.Comment: RexTex 14 pages (4 PS figures). More discussions adde
More Straightforward Extraction of the Fundamental Lepton Mixing Parameters from Long-Baseline Neutrino Oscillations
We point out the simple reversibility between the fundamental neutrino mixing
parameters in vacuum and their effective counterparts in matter. The former can
therefore be expressed in terms of the latter, allowing more straightforward
extraction of the genuine lepton mixing quantities from a variety of
long-baseline neutrino oscillation experiments. In addition to the
parametrization-independent results, we present the formulas based on the
standard parametrization of the lepton flavor mixing matrix and give a typical
numerical illustration.Comment: RevTex 10 pages. Minor changes. Phys. Rev. D in printin
Is the Cabibbo-Kobayashi-Maskawa Matrix Symmetric at the GUT Scale?
By use of the one-loop renormalization group equations and current
experimental data, we study the off-diagonal asymmetries of the
Cabibbo-Kobayashi-Maskawa (CKM) matrix at the GUT scale in the framework of the
standard model as well as its two Higgs and supersymmetric extensions. It is
concluded that the possibility of a symmetric CKM matrix at the GUT scale has
almost been ruled out.Comment: Latex 6 pages plus PS 2 pages. This tiny work would not have been put
into this archive if I had not noticed an interesting work by P. Kielanowski
et al (hep-ph/9703292), whose conclusion seems to be opposite to mine.
(Accepted for publication in J. Phys. G
Exploring the parameter space of texture 4 zero quark mass matrices
We have attempted to extend the parameter space of the elements of the
texture 4 zero Hermitian quark mass matrices, to include the case of `weak
hierarchy' amongst them along with the usually considered `strong hierarchy'
case. This has been carried out by giving wide variation to the hierarchy
defining parameters D_U and D_D, having implications for the structural
features of the mass matrices. We find that not only the weakly hierarchical
mass matrices are able to reproduce the strongly hierarchical mixing angles but
also both the phases having their origin in the mass matrices have to be non
zero to achieve compatibility of these matrices with recent quark mixing data.
Further noting the difference between the exclusive and inclusive values of
V_ub, we have carried out separate analyses corresponding to these.Comment: 13 pages, 4 figures, version accepted for publication in Journal Of
Physics
Flavor violating decays of the Higgs bosons in the THDM-III
We calculate the branching ratios for the decays of neutral Higgs bosons
() into pairs of fermions, including flavor violating
processes, in the context of the General Two Higgs Doublet Model III.Comment: 23 pages, 10 figures, 6 tables. Text clarifying equations and
references added, typos correction
Likely detection of gamma-ray pulsations of PSR~J1717+4308A in NGC~6341 and implication of the gamma-ray millisecond pulsars in globular clusters
We report our analysis results for the globular cluster (GC) NGC~6341 (M92),
as a millisecond pulsar (MSP) J17174308A has recently been reported found in
this GC. The data used are from the Large Area Telescope onboard the {\it Fermi
Gamma-ray Space Telescope (Fermi)}. We detect -ray pulsations of the
MSP at a confidence level (the corresponding weighted H-test value
is 28.4). This MSP, the fourth -ray pulsar found in a GC, does
not have significant off-pulse emission and has -ray luminosity and
efficiency \,erg\,s and 1.7\% respectively. In order
to have a clear view on the properties of the known GC -ray MSPs, we
re-analyze the \fermi\ LAT data for the other three ones. These four MSPs share
the properties of either having high (\,erg\,s)
or being in the GCs that contain only limited numbers of known MSPs. In
addition, we find that PSRs~J18233021A and B182124, in NGC~6624 and
NGC~6626 respectively, have detectable off-pulse -ray emission and PSR
J18353259B in NGC~6652 does not. Using the obtained off-pulse spectra or
spectral upper limits, we constrain the numbers of other MSPs in the four GCs.
The results are consistent with the numbers of the radio pulsars reported in
them. While at least in NGC~6624 and NGC~6626, the contribution of other MSPs
to their observed -ray emission can not be ignored, our study indicates
that the presence of a bright MSP could be the dominant factor for whether a GC
is detectable at -rays or not.Comment: 13 pages, 10 figures, 5 tables, appearing in ApJ; minor typos
correcte
Fake CPT Violation in Disappearance Neutrino Oscillations
We make an analysis of the fake CPT-violating asymmetries between the
survival probabilities of neutrinos and antineutrinos, induced by the
terrestrial matter effects, in three different scenarios of long-baseline
neutrino oscillation experiments with L=730 km, L=2100 km and L=3200 km. In
particular, the dependence of those asymmetries on the Dirac-type CP-violating
phase of the lepton flavor mixing matrix is examined.Comment: RevTex 8 pages (including 3 PS figures). To be publishe
Magnetization reversal in Kagome artificial spin ice studied by first-order reversal curves
Magnetization reversal of interconnected Kagome artificial spin ice was
studied by the first-order reversal curve (FORC) technique based on the
magneto-optical Kerr effect and magnetoresistance measurements. The
magnetization reversal exhibits a distinct six-fold symmetry with the external
field orientation. When the field is parallel to one of the nano-bar branches,
the domain nucleation/propagation and annihilation processes sensitively depend
on the field cycling history and the maximum field applied. When the field is
nearly perpendicular to one of the branches, the FORC measurement reveals the
magnetic interaction between the Dirac strings and orthogonal branches during
the magnetization reversal process. Our results demonstrate that the FORC
approach provides a comprehensive framework for understanding the magnetic
interaction in the magnetization reversal processes of spin-frustrated systems
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