2,285 research outputs found
Heavy-to-Light Meson Transitions in QCD
I discuss QCD sum rules determinations of the form factors governing the
decay . For some of these form factors the computed
dependence on the momentum transferred does not agree with the expectation from
the nearest pole dominance hypothesis. Relations are observed among the form
factors, that seem to be compatible with equations recently derived by B.Stech.
The measurement of a number of color suppressed nonleptonic B decay rates could
shed light on the accuracy of the calculation of these form factors and on the
factorization approximation.Comment: LaTex, 7 pages, 2 figures (files included). Talk given at the 6th
International Symposium on Heavy Flavours, Pisa, 6-10 June 199
Radiative transitions of and
We study radiative decays of and using
light-cone QCD sum rules. In particular, we consider the decay modes
and and evaluate the hadronic parameters in the transition
amplitudes analyzing correlation functions of scalar, pseudoscalar, vector and
axial-vector quark currents. In the case of
we also consider determinations based on two different correlation functions in
HQET. The decay widths turn out to be different than previous estimates
obtained by other methods; the results favour the interpretation of
and as ordinary mesons.Comment: RevTex, 23 pages, 9 eps figure
Properties of the DsJ states
Recent measurements involving the newly discovered D_sJ particles are
reported. The results of D_sJ production and decay branching fraction
measurements are shown. Possible spin-parity and quark content assignments of
D_sJ mesons are discussed. The results are based on a large data sample
recorded by the Belle detector at the KEKB e^+ e^- collider.Comment: 4 pages, 3 figures, proceedings to the talk given on behalf of the
Belle Collaboration at the First Meeting of the APS Topical Group on Hadron
Physic
Chiral symmetry restoration and deconfinement in QCD at finite temperature
The light-quark correlator in the axial-vector channel is used, in
conjunction with finite energy QCD sum rules at finite temperature, in order to
(a) establish a relation between chiral-symmetry restoration and deconfinement,
and (b) determine the temperature behavior of the width and
coupling. Results indicate that deconfinement takes place at a slightly lower
temperature than chiral-symmetry restoration, although this difference is not
significant given the accuracy of the method. The behaviour of the
parameters is consistent with quark-gluon deconfinement, as the width grows and
the coupling decreases with increasing temperature
The effects of enhanced Z penguins on lepton polarizations in
The sensitivity of the mode to electroweak penguins and the
recent experimental data for the , modes has given rise
to what is known as the `` puzzle''. Recently it has been observed
that this {\sl puzzle} can be resolved by considering the new physics which can
enter via penguins. In this note we analyze the effect of this enhanced
penguins on the lepton polarization asymmetries of .Comment: Published versio
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Rare Radiative Transition in QCD
We investigate the radiative transition in the
framework of QCD sum rules. In particular, we calculate the transition form
factors responsible for this decay in both weak annihilation and
electromagnetic penguin channels using the quark condensate, mixed and
two-gluon condensate diagrams as well as propagation of the soft quark in the
electromagnetic field as non-perturbative corrections. These form factors are
then used to estimate the branching ratios of the channels under consideration.
The total branching ratio of the transition is
obtained to be in order of , and the dominant contribution comes from
the weak annihilation channel.Comment: 24 Pages and 3 Figure
J/psi couplings to charmed resonances and to pi
We present an evaluation of the strong couplings JD^(*)D^(*) and
JD^(*)D^(*)pi by an effective field theory of quarks and mesons. These
couplings are necessary to calculate pi+J/psi --> D^(*)+barD^(*) cross
sections, an important background to the J/psi suppression signal in the
quark-gluon plasma. We write down the general effective lagrangian and compute
the relevant couplings in the soft pion limit and beyond.Comment: 11 pages, 4 figures, 2 reference added and minor comments, style
changed to RevTe
Cusps in K_L --> 3 pi decays
The pion mass difference generates a pronounced cusp in K --> 3 pi decays,
the strength of which is related to the pi pi S-wave scattering lengths. We
apply an effective field theory framework developed earlier to evaluate the
amplitudes for K_L --> 3 pi decays in a systematic manner, where the strictures
imposed by analyticity and unitarity are respected automatically. The
amplitudes for the decay eta --> 3 pi are also given.Comment: 15 pages, 3 figures, uses Elsevier styl
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