1,789 research outputs found
Azimuthal correlation between the and planes in the semileptonic rest frame decay of a polarized top quark: An effect
The azimuthal correlation between the planes formed by the vectors
and in the
semileptonic rest frame decay of a polarized top quark belongs to a class of polarization observables involving the
top quark which vanish at the Born term level in the standard model. We
determine the next--to--leading order QCD corrections to the afore-mentioned
azimuthal correlation and compare the result to the corresponding contribution
of a non--standard--model right--chiral quark current.Comment: latex, 12 pages with 2 figures in the text, typos removed,comment and
references added, replaced with published versio
Engineering Quantum States, Nonlinear Measurements, and Anomalous Diffusion by Imaging
We show that well-separated quantum superposition states, measurements of
strongly nonlinear observables, and quantum dynamics driven by anomalous
diffusion can all be achieved for single atoms or molecules by imaging
spontaneous photons that they emit via resonance florescence. To generate
anomalous diffusion we introduce continuous measurements driven by L\'evy
processes, and prove a number of results regarding their properties. In
particular we present strong evidence that the only stable L\'evy density that
can realize a strictly continuous measurement is the Gaussian.Comment: revtex4-1, 17 pages, 7 eps figure
Helicity Analysis of Semileptonic Hyperon Decays Including Lepton Mass Effects
Using the helicity method we derive complete formulas for the joint angular
decay distributions occurring in semileptonic hyperon decays including lepton
mass and polarization effects. Compared to the traditional covariant
calculation the helicity method allows one to organize the calculation of the
angular decay distributions in a very compact and efficient way. In the
helicity method the angular analysis is of cascade type, i.e. each decay in the
decay chain is analyzed in the respective rest system of that particle. Such an
approach is ideally suited as input for a Monte Carlo event generation program.
As a specific example we take the decay () followed by the nonleptonic decay for which we show a few examples of decay distributions which are
generated from a Monte Carlo program based on the formulas presented in this
paper. All the results of this paper are also applicable to the semileptonic
and nonleptonic decays of ground state charm and bottom baryons, and to the
decays of the top quark.Comment: Published version. 40 pages, 11 figures included in the text. Typos
corrected, comments added, references added and update
Quark and Pole Models of Nonleptonic Decays of Charmed Baryons
Quark and pole models of nonleptonic decays of charmed baryons are analysed
from the point of view of their symmetry properties. The symmetry structure of
the parity conserving amplitudes that corresponds to the contribution of the
ground-state intermediate baryons is shown to differ from the one hitherto
employed in the symmetry approach. It is pointed out that the "subtraction" of
sea quark effects in hyperon decays leads to an estimate of -exchange
contributions in charmed baryon decays that is significantly smaller than
naively expected on the basis of . An constraint questioning
the reliability of the factorization technique is exhibited. Finally, a
successful fit to the available data is presented.Comment: 25 pages, LATEX, 1643/PH IFJ Krako
Exclusive semileptonic and nonleptonic decays of the Bc meson
We study exclusive nonleptonic and semileptonic decays of the Bc-meson within
a relativistic constituent quark model previously developed by us. For the
nonleptonic decays we use the factorizing approximation. We update our model
parameters by using new experimental data for the mass and the lifetime of the
Bc meson and the leptonic decay constants of the D-meson. We calculate the
branching ratios for a large set of exclusive nonleptonic and semileptonic
decays of the meson and compare our results with the results of other
studies. As a guide for further experimental exploration we provide explicit
formulas for the full angular decay distributions in the cascade decays Bc^- =>
J/psi(=> l^+l^-) + rho^-(=> pi^- pi^0) and Bc^- => J/psi(=> l^+l^-) +
W^-(off-shell)(=> l^- + nubar).Comment: 19 pages, 2 figure
SU(3)_flavor analysis of two-body weak decays of charmed baryons
We study two-body weak decays of charmed baryons \Lambda_c and \Xi_c into an
octet or decuplet baryon and a pseudoscalar meson employing the SU(3) flavor
symmetry. Using certain measured Cabibbo-favored modes, we fix the reduced
amplitudes and predict the branching ratios of various decays of charmed
baryons in the Cabibbo-enhanced, -suppressed and -doubly suppressed modes.Comment: 25 pages, No figure, Phys. Rev. D (to appear
Exclusive Nonleptonic Decays of Bottom and Charm Baryons in a Relativistic Three-Quark Model: Evaluation of Nonfactorizing Diagrams
Exclusive nonleptonic decays of bottom and charm baryons are studied within a
relativistic three-quark model with a Gaussian shape for the momentum
dependence of the baryon-three-quark vertex. We include factorizing as well as
nonfactorizing contributions to the decay amplitudes. For heavy-to-light
transitions Q -> q u d the total contribution of the nonfactorizing diagrams
amount up to approximately 60% of the factorizing contributions in amplitude,
and up to approximately 30% for b -> c u d transitions. We calculate the rates
and the polarization asymmetry parameters for various nonleptonic decays and
compare them to existing data and to the results of other model calculations.Comment: 49 pages, LaTeX-fil
- …