5,097 research outputs found
Double-lepton polarizations in (B -> l^+ l^- gamma) decay
Double-lepton polarization asymmetries in the (B -> l^+ l^- gamma) decay are
calculated using the most general, model independent form of the effective
Hamiltonian including all possible forms of the interaction. The dependencies
of the asymmetries on new Wilson coefficients are investigated. The
detectability the averaged double-lepton polarization asymmetries at LHC is
also discussed.Comment: 20 pages, 7 PostScript figures, LaTeX formatte
Electronic spectra of polyatomic molecules with resolved individual rotational transitions
The density of rotational transitions for a polyatomic molecule is so large that in general many such
transitions are hidden under the Doppler profile, this being a fundamental limit of conventional high
resolution electronic spectroscopy. We present here the first Doppler-free cw two-photon spectrum of a
polyatomic molecule. In the case of benzene, 400 lines are observed of which 300 are due to single rotational
transitions, their spacing being weil below the Doppler profile. The resolution so achieved is 1.5 X 10'.
Benzene is a prototype planar molecule taken to have D •• symmetry in the ground as weil as in the first
excited state. From our ultra-high resolution results it is found that benzene in the excited SI state i8 a
symmetrical rotor to a high degree. A negative inertial defect is found for the excited state. The origin of this
inertial defect is discused
Constraints on Dark Photon from Neutrino-Electron Scattering Experiments
A possible manifestation of an additional light gauge boson , named
as Dark Photon, associated with a group is studied in neutrino
electron scattering experiments. The exclusion plot on the coupling constant
and the dark photon mass is obtained. It is shown
that contributions of interference term between the dark photon and the
Standard Model are important. The interference effects are studied and compared
with for data sets from TEXONO, GEMMA, BOREXINO, LSND as well as CHARM II
experiments. Our results provide more stringent bounds to some regions of
parameter space.Comment: 22 pages, 6 figures, 2 tables, text improved, fig.6 updated,
references adde
Sparsity of integer solutions in the average case
We examine how sparse feasible solutions of integer programs are, on average. Average case here means that we fix the constraint matrix and vary the right-hand side vectors. For a problem in standard form with m equations, there exist LP feasible solutions with at most m many nonzero entries. We show that under relatively mild assumptions, integer programs in standard form have feasible solutions with O(m) many nonzero entries, on average. Our proof uses ideas from the theory of groups, lattices, and Ehrhart polynomials. From our main theorem we obtain the best known upper bounds on the integer Carathéodory number provided that the determinants in the data are small
Double-Lepton Polarization Asymmetries and Branching Ratio of the B\rar \gamma l^+ l^- transition in Universal Extra Dimension
We study the radiative dileptonic B \rar \gamma l^+ l^- transition in the
presence of a universal extra dimension in the Applequist-Cheng-Dobrescu model.
In particular, using the corresponding form factors calculated via light cone
QCD sum rules, we analyze the branching ratio and double lepton polarization
asymmetries related to this channel and compare the results with the
predictions of the standard model. We show how the results deviate from
predictions of the standard model at lower values of the compactification
factor () of extra dimension.Comment: 20 Pages and 8 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
The scalar unparticle effect on the charged lepton electric dipole moment
We study the charged lepton electric dipole moment which is induced by the
scalar unparticle mediation and we predict the appropriate range for the free
parameters appearing in the effective lagrangian which drives the
unparticle-standard model lepton interactions. We observe that the charged
lepton electric dipole moment is strongly sensitive to the scaling dimension
d_u of the unparticle and the new couplings in the effective interaction.
Furthermore, we see that the current experimental limits of charged lepton
electric dipole moments can ensure an appropriate range for these free
parameters.Comment: 19 pages, 13 Figure
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