2,446 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
On duality and reflection factors for the sinh-Gordon model
The sinh-Gordon model with integrable boundary conditions is considered in
low order perturbation theory. It is pointed out that results obtained by
Ghoshal for the sine-Gordon breather reflection factors suggest an interesting
dual relationship between models with different boundary conditions. Ghoshal's
formula for the lightest breather is checked perturbatively to in
the special set of cases in which the symmetry is maintained.
It is noted that the parametrisation of the boundary potential which is natural
for the semi-classical approximation also provides a good parametrisation at
the `free-fermion' point.Comment: 17 pages, harvmac(b
Higgs-Inflaton Potential in Higher-Dimensional SUSY Gauge Theories
We study the possibility that the Higgs and the inflaton are the same single
field or cousins arising from the extra space components of some
higher-dimensional gauge field. We take 5D supersymmetric gauge theory with a
matter compactified on S^1 as a toy model and evaluate the one-loop
contribution to the Higgs-inflaton potential. Our gauge-Higgs-inflaton
unification picture applied to the gauge field of intermediate energy scale
(\sim 10^{13} GeV) can explain the observed inflation parameters without
fine-tuning.Comment: 10 pages, 3 figures, Title and abstract are slightly changed. Our
results are also modifie
Magnetic ordering and fluctuation in kagome lattice antiferromagnets, Fe and Cr jarosites
Jarosite family compounds, KFe_3(OH)_6(SO_4)_2, (abbreviate Fe jarosite), and
KCr_3(OH)_6(SO_4)_2, (Cr jarosite), are typical examples of the Heisenberg
antiferromagnet on the kagome lattice and have been investigated by means of
magnetization and NMR experiments. The susceptibility of Cr jarosite deviates
from Curie-Weiss law due to the short-range spin correlation below about 150 K
and shows the magnetic transition at 4.2 K, while Fe jarosite has the
transition at 65 K. The susceptibility data fit well with the calculated one on
the high temperature expansion for the Heisenberg antiferromagnet on the kagome
lattice. The values of exchange interaction of Cr jarosite and Fe jarosite are
derived to be J_Cr = 4.9 K and J_Fe = 23 K, respectively. The 1H-NMR spectra of
Fe jarosite suggest that the ordered spin structure is the q = 0 type with
positive chirality of the 120 degrees configuration. The transition is caused
by a weak single-ion type anisotropy. The spin-lattice relaxation rate, 1/T_1,
of Fe jarosite in the ordered phase decreases sharply with lowering the
temperature and can be well explained by the two-magnon process of spin wave
with the anisotropy.Comment: REVTeX, 14 pages with 5 figures. Submitted to Canadian Journal of
Physic
Resonant inelastic x-ray scattering study of hole-doped manganites La1-xSrxMnO3 (x=0.2 and 0.4)
Electronic excitations near the Fermi energy in the hole doped manganese
oxides (La1-xSrxMnO3, x=0.2 and 0.4) have been elucidated by using the resonant
inelastic x-ray scattering (RIXS) method. A doping effect in the strongly
correlated electron systems has been observed for the first time. The
scattering spectra show that a salient peak appears in low energies indicating
the persistence of the Mott gap. At the same time, the energy gap is partly
filled by doping holes and the energy of the spectral weight shifts toward
lower energies. The excitation spectra show little change in the momentum space
as is in undoped LaMnO3, but the scattering intensities in the low energy
excitations of x=0.2 are anisotropic as well as temperature dependent, which
indicates a reminiscence of the orbital nature
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
Momentum Dependent Charge Excitations of Two-Leg Ladder: Resonant Inelastic X-ray Scattering of (La,Sr,Ca)14Cu24O41
Momentum dependent charge excitations of a two-leg ladder are investigated by
resonant inelastic x-ray scattering of (La,Sr,Ca)14Cu24O41. In contrast to the
case of a square lattice, momentum dependence of the Mott gap excitation of the
ladder exhibits little change upon hole-doping, indicating the formation of
hole pairs. Theoretical calculation based on a Hubbard model qualitatively
explains this feature. In addition, experimental data shows intraband
excitation as continuum intensity below the Mott gap and it appears at all the
momentum transfers simultaneously. The intensity of the intraband excitation is
proportional to the hole concentration of the ladder, which is consistent with
optical conductivity measurements.Comment: 7 page
Development of a carbon dioxide-water solid oxide electrolyte electrolysis system Annual report, 29 Mar. 1968 - 29 May 1969
Carbon dioxide-water solid oxide electrolyte electrolysis syste
The Gauge Hierarchy Problem and Higher Dimensional Gauge Theories
We report on an attempt to solve the gauge hierarchy problem in the framework
of higher dimensional gauge theories. Both classical Higgs mass and
quadratically divergent quantum correction to the mass are argued to vanish.
Hence the hierarchy problem in its original sense is solved. The remaining
finite mass correction is shown to depend crucially on the choice of boundary
condition for matter fields, and a way to fix it dynamically is presented. We
also point out that on the simply-connected space even the finite mass
correction vanishes.Comment: LaTeX2e. 12 pages, 3 Postscript figures; Added references, some
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