6,029 research outputs found
General analysis of the rare Bc->D^*_s l^+ l^- decay beyond the standard model
The general analysis of the rare Bc->D^*_s l^+ l^- decay is presented by
using the most general, model independent effective Hamiltonian. The
dependencies of the branching ratios, longitudinal, normal and transversal
polarization asymmetries for l^- and the combined asymmetries for l^- and l^+
on the new Wilson coefficients are investigated. Our analysis shows that the
lepton polarization asymmetries are very sensitive to the scalar and tensor
type interactions, which will be very useful in looking for new physics beyond
the standard model.Comment: 27 Pages, 14 Figure
Lepton polarization correlations in
In this work we will study the polarizations of both leptons () in the
decay channel . In the case of the dileptonic inclusive
decay , where apart from the polarization asymmetries
of single lepton , one can also observe the polarization asymmetries of
both leptons simultaneously. If this sort of measurement is possible then we
can have, apart from decay rate, FB asymmetry and the six single lepton
polarization asymmetries (three each for and ), nine more
double polarization asymmetries. This will give us a very useful tool in more
strict testing of SM and the physics beyond. We discuss the double polarization
asymmetries of leptons in the decay mode within
the SM and the Minimal Supersymmetric extensions of it.Comment: 21 pages, 21 figures; version to match paper to appear in PR
Transient lateral photovoltaic effect in patterned metal-oxide-semiconductor films
The time dependent transient lateral photovoltaic effect has been studied
with us time resolution and with chopping frequencies in the kHz range, in
lithographically patterned 21 nm thick, 5, 10 and 20 um wide and 1500 um long
Co lines grown over naturally passivated p-type Si (100). We have observed a
nearly linear dependence of the transitorial response with the laser spot
position. A transitorial response with a sign change in the laser-off stage has
been corroborated by numerical simulations. A qualitative explanation suggests
a modification of the drift-diffusion model by including the in uence of a
local inductance. Our findings indicate that the microstructuring of position
sensitive detectors could improve their space-time resolution.Comment: 4 pages, 4 figure
Instabilities for a relativistic electron beam interacting with a laser irradiated plasma
The effects of a radiation field (RF) on the unstable modes developed in
relativistic electron beam--plasma interaction are investigated assuming that
, where is the frequency of the RF and
is the plasma frequency. These unstable modes are parametrically
coupled to each other due to the RF and are a mix between two--stream and
parametric instabilities. The dispersion equations are derived by the
linearization of the kinetic equations for a beam--plasma system as well as the
Maxwell equations. In order to highlight the effect of the radiation field we
present a comparison of our analytical and numerical results obtained for
nonzero RF with those for vanishing RF. Assuming that the drift velocity
of the beam is parallel to the wave vector of the
excitations two particular transversal and parallel configurations of the
polarization vector of the RF with respect to are
considered in detail. It is shown that in both geometries resonant and
nonresonant couplings between different modes are possible. The largest growth
rates are expected at the transversal configuration when is
perpendicular to . In this case it is demonstrated that in general
the spectrum of the unstable modes in -- plane is split into two
distinct domains with long and short wavelengths, where the unstable modes are
mainly sensitive to the beam or the RF parameters, respectively. In parallel
configuration, , and at short wavelengths
the growth rates of the unstable modes are sensitive to both beam and RF
parameters remaining insensitive to the RF at long wavelengths.Comment: 23 pages, 5 figure
Temperature dependent dynamic and static magnetic response in magnetic tunnel junctions with Permalloy layers
Ferromagnetic resonance and static magnetic properties of CoFe/Al2O3/CoFe/Py
and CoFe/Al2O3/CoFeB/Py magnetic tunnel junctions and of 25nm thick
single-layer Permalloy(Py) films have been studied as a function of temperature
down to 2K. The temperature dependence of the ferromagnetic resonance excited
in the Py layers in magnetic tunnel junctions shows knee-like enhancement of
the resonance frequency accompanied by an anomaly in the magnetization near
60K. We attribute the anomalous static and dynamic magnetic response at low
temperatures to interface stress induced magnetic reorientation transition at
the Py interface which could be influenced by dipolar soft-hard layer coupling
through the Al2O3 barrier
A Slowly Rotating Charged Black Hole in Five Dimensions
Black hole solutions in higher dimensional Einstein and Einstein-Maxwell
gravity have been discussed by Tangherlini as well as Myers and Perry a long
time ago. These solutions are the generalizations of the familiar
Schwarzschild, Reissner-Nordstrom and Kerr solutions of four-dimensional
general relativity. However, higher dimensional generalization of the
Kerr-Newman solution in four dimensions has not been found yet. As a first step
in this direction I shall report on a new solution of the Einstein-Maxwell
system of equations that describes an electrically charged and slowly rotating
black hole in five dimensions.Comment: Talk given at GR17: 17th International Conference on General
Relativity and Gravitation, Dublin, 18-24 Jule,2004 ; Corrected typos, minor
changes, new formula adde
Properties of the Discrete Hilbert Transform
The asymptotic behavior of the distribution function of the Hilbert transform of
sequences from the class l1 is studied. The concept of Q-summability of series is
introduced; using this notion, it is shown that the Hilbert transform of a sequence from
the class l1 is Q-summable and is Q-sum is zero
Low frequency noise due to magnetic inhomogeneities in submicron FeCoB/MgO/FeCoB magnetic tunnel junctions
We report on room temperature low frequency noise due to magnetic
inhomogeneities/domain walls (MI/DWs) in elliptic submicron FeCoB/MgO/FeCoB
magnetic tunnel junctions with an area between 0.0245 and 0.0675{\mu}m2. In the
smaller area junctions we found an unexpected random telegraph noise (RTN1),
deeply in the parallel state, possibly due to stray field induced MI/DWs in the
hard layer. The second noise source (RTN2) is observed in the antiparallel
state for the largest junctions. Strong asymmetry of RTN2 and of related
resistance steps with current indicate spin torque acting on the MI/DWs in the
soft layer at current densities below 5x10^5 A/cm2.Comment: 12 pages, 4 figure
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