2,256 research outputs found
Implications of the non-universal Z boson in FCNC mediated rare decays
We analyze the effect of the non-universal boson in the rare decays , and decays. These
decays involve the FCNC mediated transitions, and are found to be
very small in the standard model. The smallness of these decays in the standard
model makes them sensitive probe for new physics. We find an enhancement of at
least an order in these branching ratios because of the non-universal
coupling.Comment: 15 pages, 4 figures, minor changes in the text, references added, to
appear in PR
Study of basic bio-electrochemistry Sixth monthly progress report, 1-31 Aug. 1963
Contribution of hydrogen peroxide to electrode reaction in electrochemical cell by considering effect of catalyst on cell curren
Improving bounds on flavor changing vertices in the two Higgs doublet model from mixing
We find some constraints on the flavor changing vertices of the two Higgs
doublet model, from the \Delta M_{B_{d}} measurement. Although bounds from this
observable have already been considered, this paper takes into account the role
of a new operator not included previously, as well as the vertices \xi_{bb},
\xi_{tc} and \xi_{sb}. Using the Cheng-Sher parametrization, we found that for
a relatively light charged Higgs boson (200-300 GeV), we get that \lambda
_{tt}<1, while the parameter \lambda_{bb} could have values up to about 50. In
addition, we use bounds for \lambda_{tt} and \lambda_{bb} obtained from
B^{0}->X_{s}\gamma at next to leading order, and studied the case where the
only vanishing vertex factors are the ones involving quarks from the first
family. We obtained that \Delta M_{B_{d}} is not sensitive to the change of the
parameter \lambda_{sb}, while \lambda_{tc}<1Comment: 4 pages, 1 figure, LaTeX2
Examination of the Resonance Contributions to Dileptonic Rare B-Decays
We analyse the long-distance contribution to
differential decay rate when the momentum dependence of and
- conversion strength is taken into account. The results
indicate that the resonance to nonresonance interference in the dilepton
invariant mass distribution is substantially reduced.Comment: 10 pages, Latex, one figure (included
Orbital polaron lattice formation in lightly doped La1-xSrxMnO3
By resonant x-ray scattering at the Mn K-edge on La7/8Sr1/8MnO3, we show that
an orbital polaron lattice (OPL) develops at the metal-insulator transition of
this compound. This orbital reordering explains consistently the unexpected
coexistence of ferromagnetic and insulating properties at low temperatures, the
quadrupling of the lattice structure parallel to the MnO2-planes, and the
observed polarization and azimuthal dependencies. The OPL is a clear
manifestation of strong orbital-hole interactions, which play a crucial role
for the colossal magnetoresistance effect and the doped manganites in general
Atomic displacements and lattice distortion in the magnetic-field-induced charge ordered state of SmRuP
Structural properties of SmRuP in the anomalous magnetic ordered
phase between K and K in magnetic fields has
been studied by x-ray diffraction. Atomic displacements of Ru and P, reflecting
the field-induced charge order of the electrons, have been deduced by
analyzing the intensities of the forbidden Bragg peaks, assuming a cubic space
group . Also, by utilizing high-resolution x-ray diffraction
experiment, we observed a splitting of fundamental Bragg peaks, clarifying that
the unit cell in the magnetic ordered phase is rhombohedral elongated along the
axis. Responses of the rhombohedral domains to the magnetic
field, which reflects the direction of the magnetic moment, is studied in
detail.Comment: 11 pages, 11 figures, accepted for publication in PR
Lepton-Flavour Violation in Ordinary and Supersymmetric Grand Unified Theories
By an explicit calculation we show that in ordinary SU(5) logarithmic
divergence in the amplitude of cancels among diagrams and
remaining finite part is suppressed by at least . In SUSY SU(5),
when the effect of flavour changing wave function renormalization is taken into
account such logarithmic correction disappears, provided a condition is met
among SUSY breaking masses. In SUGRA-inspired SUSY GUT the remaining
logarithmic effect is argued not to be taken as a prediction of the theory.Comment: 8 pages, LaTeX209 file, using axodraw.st
Moose models with vanishing parameter
In the linear moose framework, which naturally emerges in deconstruction
models, we show that there is a unique solution for the vanishing of the
parameter at the lowest order in the weak interactions. We consider an
effective gauge theory based on SU(2) gauge groups, chiral fields and
electroweak groups and at the ends of the chain of the
moose. vanishes when a link in the moose chain is cut. As a consequence one
has to introduce a dynamical non local field connecting the two ends of the
moose. Then the model acquires an additional custodial symmetry which protects
this result. We examine also the possibility of a strong suppression of
through an exponential behavior of the link couplings as suggested by Randall
Sundrum metric.Comment: LaTex file, 27 pages, 8 figure
Decay and Supersymmetry
The inclusive radiative -decay is a sensitive probe of new physics,
especially if related to the virtual exchange of a charged Higgs boson.
Supersymmetric models provide a particularly interesting example. In the limit
of exact supersymmetry, BR()~=~0, due to the vanishing of any
magnetic-moment transition operator. We illustrate the impact of this
constraint for realistic values of the supersymmetry-breaking parameters.Comment: 7 pages, CERN-TH.6830/93 (Minor changes; a comment on the case >1 has been added
Slow Relaxation Process in Ising like Heisenberg Kagome Antiferromagnets due to Macroscopic Degeneracy in the Ordered State
We study relaxation phenomena in the ferromagnetically ordered state of the
Ising-like Heisenberg kagome antiferromagnets. We introduce the "weathervane
loop" in order to characterize macroscopic degenerate ordered states and study
the microscopic mechanism of the slow relaxation from a view point of the
dynamics of the weathervane loop configuration. This mechanism may give a
possible origin of the slow relaxation reported in recent experiments.Comment: 6pages, 4figures, HFM2006 proceeding
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