241 research outputs found
Corrections to the generalized vector dominance due to diffractive rho_3 production
The idea of the vector dominance is still in use in various analyses of
experimental data of photon-hadron reactions. It makes sense, therefore, to
recast results of microscopic calculations of such reactions in this language.
Here we present the diffractive DIS production as a specific
correction to the generalized vector dominance. We perform a coupled channel
analysis of spin-orbital excitations in diffractive photoproduction and
reiterate the point that rho_3 in diffractive DIS will be sensitive to a novel
aspect of diffraction.Comment: 12 pages, 2 figure
Hadronic Charmed Meson Decays Involving Tensor Mesons
Charmed meson decays into a pseudoscalar meson P and a tensor meson T are
studied. The charm to tensor meson transition form factors are evaluated in the
Isgur-Scora-Grinstein-Wise (ISGW) quark model. It is shown that the
Cabibbo-allowed decay is dominated by the
W-annihilation contribution and has the largest branching ratio in
decays. We argue that the Cabibbo-suppressed mode
should be suppressed by one order of magnitude relative to . When the finite width effect of the tensor resonances is taken
into account, the decay rate of is generally enhanced by a factor of
. Except for , the predicted branching ratios
of decays are in general too small by one to two orders of magnitude
compared to experiment. However, it is very unlikely that the
transition form factors can be enhanced by a factor of within the
ISGW quark model to account for the discrepancy between theory and experiment.
As many of the current data are still preliminary and lack sufficient statistic
significance, more accurate measurements are needed to pin down the issue.Comment: 11 page
Nonresonant Three-body Decays of D and B Mesons
Nonresonant three-body decays of D and B mesons are studied. It is pointed
out that if heavy meson chiral perturbation theory (HMChPT) is applied to the
heavy-light strong and weak vertices and assumed to be valid over the whole
kinematic region, then the predicted decay rates for nonresonant charmless
3-body B decays will be too large and especially B^- --> pi^- K^+ K^- greatly
exceeds the current experimental limit. This can be understood as chiral
symmetry has been applied there twice beyond its region of validity. If HMChPT
is applied only to the strong vertex and the weak transition is accounted for
by the form factors, the dominant B^* pole contribution to the tree-dominated
direct three-body B decays will become small and the branching ratio will be of
order 10^{-6}. The decay modes B^- --> (K^- h^+ h^-)_{NR} and bar{B}^0 -->
(bar{K}^0 h^+h^-)_{NR} for h = pi, K are penguin dominated. We apply HMChPT in
two different cases to study the direct 3-body D decays and compare the results
with experiment. Theoretical uncertainties are discussed.Comment: 24 pages, 2 figures. New experimental results of direct 3-body D
decays as Reported at ICHEP2002 are included. To appear in Phys. Re
Role of Charm Factory in Extracting CKM-Phase Information via B --> DK
In this paper we study the impact of data that can be obtained from a Charm
Factory on the determination of the CKM parameter gamma from decays of the form
B -> D0 K where the D0 decays to specific inclusive and exclusive final states.
In particular, for each exclusive final state , the charm factory can
determine the strong phase difference between D0-> f and D0-bar -> f by
exploiting correlations in psi(3770)-> D0 D0-bar. This provides crucial input
to the determination of gamma via the interference of B+- -> K+- D0 -> f with
B+- -> K+- D0-bar -> f. We discuss how the method may be generalized to
inclusive final states and illustrate with a toy model how such methods may
offer one of the best means to determine gamma with 10^8-10^9 B-mesons.Comment: 12 pages, 7 figures, Version 2: Fixed typos; add reference; Version
3: fixed latex glitc
Nonfactorization and the decays and
In six chosen scenarios for the dependence of the form factors involved
in transition, we have determined the allowed domain
of and from the experimentally measured
ratios and in a scheme that uses the value of the phenomenological parameter and includes nonfactorized
contribution. We find that the experimentally measured values of and
from semileptonic decays of favor solutions which have significant
nonfactorized contribution, and, in particular, favors solutions in
scenarios where is either flat or decreasing with .Comment: 15 pages, Latex, four figure (available on request)
Two-Body Cabibbo-Suppressed Charmed Meson Decays
Singly-Cabibbo-suppressed decays of charmed particles governed by the quark
subprocesses and are analyzed using a
flavor-topology approach, based on a previous analysis of the Cabibbo-favored
decays governed by . Decays to and , where is a
pseudoscalar meson and is a vector meson, are considered. We include
processes in which and are produced.Comment: 18 pages, latex, 2 figures, to be submitted to Phys. Rev.
Resonant and nonresonant D+ -> K- pi+ l+ nu(l) semileptonic decays
We analyse the semileptonic decay D+ -> K- pi+ l+ nu(l) using an effective
Lagrangian developed previously to describe the decays D -> P l nu(l) and D ->
V l nu(l). Light vector mesons are included in the model which combines the
heavy quark effective Lagrangian and chiral perturbation theory approach. The
nonresonant and resonant contributions are compared. With no new parameters the
model correctly reproduces the measured ratio Gamma(nres)/Gamma(nres + res). We
also present useful nonresonant decay distributions. Finally, a similar model,
but with a modified current which satisfies the soft pion theorems at the
expense of introducing another parameter, is analyzed and the results of the
models are compared.Comment: 17 pages, 3 Postscript figures, standard Latex, extended revision,
title, abstract and text (especially Sec. IV) changed, results unchange
Comments on the Quark Content of the Scalar Meson
Based on the measurements of we determine, in
a model independent way, the allowed content in the scalar meson
. We find that, on the one hand, if this isoscalar resonance is a
pure state [ , a very
large -annihilation term will be needed to accommodate . On the other hand, the component of
should be small enough to avoid excessive induced
from the external -emission. Measurement of production in the
decay will be useful to test the above picture. For the
decay which is kinematically barely or even not
allowed, depending on the mass of , we find that the finite width
effect of plays a crucial role on the resonant three-body decay
.Comment: 12 pages, 2 figure
Determining using with multibody D decays
We propose a method for determining using decays
followed by a multibody decay, such as , and . The main advantages of the method is
that it uses only Cabibbo allowed decays, and that large strong phases are
expected due to the presence of resonances. Since no knowledge about the
resonance structure is needed, can be extracted without any hadronic
uncertainty.Comment: 17 pages, 1 figur
Measuring the Relative Strong Phase in and Decays
In a recently suggested method for measuring the weak phase in
decays, the relative strong phase in and decays (equivalently, in and \od \to K^{*+} K^-) plays a role. It is shown how a study of
the Dalitz plot in can yield information on this phase,
and the size of the data sample which would give a useful measurement is
estimated.Comment: 13 pages, latex, 5 figures, submitted to Phys. Rev. D. Appendix and
some text on additional resonant contributions adde
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