4,236 research outputs found
New physics effects to the lepton polarizations in the B -> K l^+ l^- decay
Using the general, model independent form of the effective Hamiltonian, the
general expressions of the longitudinal, normal and transversal polarization
asymmetries for (l^-) and (l^+) and combinations of them for the exclusive (B
-> K l^+ l^-) decay are found. The sensitivity of lepton polarizations and
their combinations on new Wilson coefficients are studied. It is found that
there exist regions of Wilson coefficients for which the branching ratio
coincides with the Standard Model result while the lepton polarizations differ
substantially from the standard model prediction. Hence, studying lepton
polarization in these regions of new Wilson coefficients can serve as a
promising tool for establishing new physics beyond the Standard Model.Comment: 18 pp, 14 figures (postscript formatted), LaTex formatte
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
Topologically massive magnetic monopoles
We show that in the Maxwell-Chern-Simons theory of topologically massive
electrodynamics the Dirac string of a monopole becomes a cone in anti-de Sitter
space with the opening angle of the cone determined by the topological mass
which in turn is related to the square root of the cosmological constant. This
proves to be an example of a physical system, {\it a priory} completely
unrelated to gravity, which nevertheless requires curved spacetime for its very
existence. We extend this result to topologically massive gravity coupled to
topologically massive electrodynamics in the framework of the theory of Deser,
Jackiw and Templeton. These are homogeneous spaces with conical deficit. Pure
Einstein gravity coupled to Maxwell-Chern-Simons field does not admit such a
monopole solution
Vacuum Fluctuations of a massless spin-1/2 field around multiple cosmic strings
We study the interaction of a massless quantized spinor field with the
gravitational filed of N parallel static cosmic strings by using a perturbative
approach. We show that the presence of more than one cosmic string gives rise
to an additional contribution to the energy density of vacuum fluctuations,
thereby leading to a vacuum force attraction between two parallel cosmic
strings.Comment: Class. Quantum Grav. 14(1997) 321
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
Charmonium-hadron interactions from QCD
The heavy quark system is an excellent probe to learn about the QCD dynamics
at finite density. First, we discuss the properties of the and
meson at finite nucleon density. We discuss why their properties should change
at finite density and then introduce an exact QCD relation among these hadron
properties and the energy momentum tensor of the medium. Second, we discuss
attempts to calculate charmonium-hadron total cross section using effective
hadronic models and perturbative QCD. We emphasize a recent calculation, where
the cross section is derived using QCD factorization theorem. We conclude by
discussing some challenges for SIS 200.Comment: 8 pages, Presented at 6th International Conference on Strange Quarks
in Matter: 2001: A Flavorspace Odyssey (SQM2001), Frankfurt, Germany, 25-29
Sep 2001, submitted to J. Phys.
The CP asymmetry for B--> K^* l^+ l^- decay in the general two Higgs doublet model
We study CP asymmetry for the exclusive decay B --> K^* l^+ l^- in the two
Higgs doublet model with three level flavor changing neutral currents (model
III). We analyse the dependency of this quantity to the new phase coming from
the complex Yukawa couplings in the theory and we find that there exist a
considerable CP violation for the relevant process. Further, we see that the
sign of the Wilson coefficient C_7^{eff} can be determined by fixing dilepton
mass. Therefore, the future measurements of CP asymmetry for B --> K^* l^+ l^-
decay will give a powerful information about the sign of Wilson coefficient
C_{7}^{eff} and the new physics beyond the SM.Comment: 22 pages, 8 figure
Vacuum fluctuations for spherical gravitational impulsive waves
We propose a method for calculating vacuum fluctuations on the background of
a spherical impulsive gravitational wave which results in a finite expression
for the vacuum expectation value of the stress-energy tensor. The method is
based on first including a cosmological constant as an auxiliary constant. We
show that the result for the vacuum expectation value of the stress-energy
tensor in second-order perturbation theory is finite if both the cosmological
constant and the infrared parameter tend to zero at the same rate.Comment: Class. Quantum Grav. 13(1996) 2683-269
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