1,183 research outputs found
A Systematic Analysis of the Lepton Polarization Asymmetries in the Rare B Decay, B -> X_s\tau^+\tau^-
The most general model-independent analysis of the lepton polarization
asymmetries in the rare B decay, \Bstt, is presented. We present the
longitudinal, normal and transverse polarization asymmetries for the
and , and combinations of them, as functions of the Wilson coefficients
of twelve independent four-Fermi interactions, ten of them local and two
nonlocal. These procedures will tell us which type of operators contributes to
the process. And it will be very useful to pin down new physics systematically,
once we have the experimental data with high statistics and a deviation from
the Standard Model is found.Comment: 24 pages, 8 figures, LaTe
First demonstration of the gain switching characteristics of an AlGaAs–GaAs V-grooved quantum wire laser
Regular black hole in three dimensions
We find a new black hole in three dimensional anti-de Sitter space by
introducing an anisotropic perfect fluid inspired by the noncommutative black
hole. This is a regular black hole with two horizons. We compare thermodynamics
of this black hole with that of non-rotating BTZ black hole. The first-law of
thermodynamics is not compatible with the Bekenstein-Hawking entropy.Comment: 15 pages, 16 figures, 3D noncommutative black hole included as Sec 4,
a version to appear in EPJ
Thermodynamics and evaporation of the noncommutative black hole
We investigate the thermodynamics of the noncommutative black hole whose
static picture is similar to that of the nonsingular black hole known as the de
Sitter-Schwarzschild black hole. It turns out that the final remnant of
extremal black hole is a thermodynamically stable object. We describe the
evaporation process of this black hole by using the noncommutativity-corrected
Vaidya metric. It is found that there exists a close relationship between
thermodynamic approach and evaporation process.Comment: 16 pages, 6 figures, added references, to appear in JHE
The g-2 of the Muon in Localized Gravity Models
The (g-2) of the muon is well known to be an important model building
constraint on theories beyond the Standard Model. In this paper, we examine the
contributions to arising in the Randall-Sundrum model of localized
gravity for the case where the Standard Model gauge fields and fermions are
both in the bulk. Using the current experimental world average measurement for
, we find that strong constraints can be placed on the mass of the
lightest gauge Kaluza-Klein excitation for a narrow part of the allowed range
of the assumed universal 5-dimensional fermion mass parameter, . However,
employing both perturbativity and fine-tuning constraints we find that we can
further restrict the allowed range of the parameter to only one fourth of
its previous size. The scenario with the SM in the RS bulk is thus tightly
constrained, being viable for only a small region of the parameter space.Comment: 16 pages, 2 figs, LaTex, Additional discussion adde
A Method to Monitor Local Changes in MR Signal Intensity in Articular Cartilage: A Potential Marker for Cartilage Degeneration in Osteoarthritis
Experimental Probes of Localized Gravity: On and Off the Wall
The phenomenology of the Randall-Sundrum model of localized gravity is
analyzed in detail for the two scenarios where the Standard Model (SM) gauge
and matter fields are either confined to a TeV scale 3-brane or may propagate
in a slice of five dimensional anti-deSitter space. In the latter instance, we
derive the interactions of the graviton, gauge, and fermion Kaluza-Klein (KK)
states. The resulting phenomenological signatures are shown to be highly
dependent on the value of the 5-dimensional fermion mass and differ
substantially from the case where the SM fields lie on the TeV-brane. In both
scenarios, we examine the collider signatures for direct production of the
graviton and gauge KK towers as well as their induced contributions to
precision electroweak observables. These direct and indirect signatures are
found to play a complementary role in the exploration of the model parameter
space. In the case where the SM field content resides on the TeV-brane, we show
that the LHC can probe the full parameter space and hence will either discover
or exclude this model if the scale of electroweak physics on the 3-brane is
less than 10 TeV. We also show that spontaneous electroweak symmetry breaking
of the SM must take place on the TeV-brane.Comment: 62 pages, Latex, 22 figure
Lepton Polarization and Forward-Backward Asymmetries in b -> s tau+ tau-
We study the spin polarizations of both tau leptons in the decay b -> s tau+
tau-. In addition to the polarization asymmetries involving a single tau, we
construct asymmetries for the case where both polarizations are simultaneously
measured. We also study forward-backward asymmetries with polarized tau's. We
find that a large number of asymmetries are predicted to be large, >~ 10%. This
permits the measurement of all Wilson coefficients and the b-quark mass, thus
allowing the standard model (SM) to be exhaustively tested. Furthermore, there
are many unique signals for the presence of new physics. For example,
asymmetries involving triple-product correlations are predicted to be tiny
within the SM, O(10^{-2}). Their observation would be a clear signal of new
physics.Comment: 21 pages, LaTeX, 4 figures (included). Paper somewhat reorganized,
references greatly expanded, conclusions unchange
Influence of Carbon Concentration on the Superconductivity in MgCxNi3
The influence of carbon concentration on the superconductivity (SC) in
MgCNi has been investigated by measuring the low temperature specific
heat combined with first principles electronic structure calculation. It is
found that the specific heat coefficient of the
superconducting sample () in normal state is twice that of the
non-superconducting one (). The comparison of measured
and the calculated electronic density of states (DOS) shows that the
effective mass renormalization changes remarkably as the carbon concentration
changes. The large mass renormalization for the superconducting sample and the
low (7K) indicate that more than one kind of boson mediated
electron-electron interactions exist in MgCNi.Comment: 4 pages, 4 figure
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