759 research outputs found
Multichannel calculation for Ds* vector states and the Ds(2632) resonance
We study bound states below threshold and resonances above threshold in the
D0-K+ and Ds-eta systems, using a many-coupled-channel model for non-exotic
meson-meson scattering applied to states with the quantum numbers of c-sbar
quark-antiquark vector mesons. We fit the ground state at 2.112 GeV, whence the
lowest resonances in D0-K+ come out at 2.61, 2.72, 3.03, and 3.08 GeV. The
resonance at 2.61 GeV acquires a width of about 8 MeV, while its partial P-wave
cross section is up to six times larger in Ds-eta than in D0-K+, provided a
mechanism accounting for Okubo-Zweig-Iizuka--forbidden decays is included. The
latter finding is in agreement with the observations of the SELEX collaboration
with respect to the recently reported DsJ(2632) resonance. Therefore, we
conclude that the DsJ(2632) is most probably the first recurrence excitation of
the Ds*(2112) meson.Comment: 11 pages, 6 figures; v2: Significant improvements for threshold
behavior, and for the hadronic widths by including additional two-meson
channels. Misprints in formulas correcte
Coupling constants and transition potentials for hadronic decay modes of a meson
Within the independent-harmonic-oscillator model for quarks inside a hadron,
a rigorous method is presented for the calculation of coupling constants and
transition potentials for hadronic decay, as needed in a multi-channel
description of mesons.Comment: 19 pages, 4 figure
Multichannel calculation of the very narrow and the very broad
The narrow (2317) and broad (2300-2400) charmed
scalar mesons and their radial excitations are described in a coupled-channel
quark model that also reproduces the properties of the light scalar nonet. All
two-meson channels containing ground-state pseudoscalars and vectors are
included. The parameters are chosen fixed at published values, except for the
overall coupling constant , which is fine-tuned to reproduce the
(2317) mass, and a damping constant for subthreshold
contributions. Variations of and (2300-2400) pole
postions are studied for different values. Calculated cross sections
for -wave and scattering, as well as resonance pole positions,
are given for the value of that fits the light scalars. The thus
predicted radially excited state (2850), with a width of about 50
MeV, seems to have been observed already.Comment: 3 pages, EPJ LaTeX, 2 Postscript figures, 1 table; parallel talk at
the IVth International Conference on Quarks and Nuclear Physics (QNP06),
Madrid, 5-10 June 200
A very broad X(4260) and the resonance parameters of the 3D vector charmonium state
We argue that the X(4260) enhancement contains a wealth of information on
vector c-cbar spectroscopy. We discuss the shape of the X(4260) observed in the
OZI-forbidden process "electron-positron into J/psi and a pair of charged
pions", in particular at and near vector charmonium resonances as well as
open-charm threshold enhancements. The resulting very broad X(4260) structure
does not seem to classify itself as a vector charmonium resonance, but its
detailed shape allows to identify new vector c-cbar states. Here, we estimate
the resonance parameters of the psi(3D) state.Comment: 4 pages, 5 figures; version 2: 2 figures replace
D_{sJ}(2860) as the first radial excitation of the D_{s0}^*(2317)
A coupled-channel model previously employed to describe the narrow
(2317) and broad (2400) charmed scalar mesons is generalized
so as to include all ground-state pseudoscalar-pseudoscalar and vector-vector
two-meson channels. All parameters are chosen fixed at published values, except
for the overall coupling constant, which is fine-tuned to reproduce the
(2317) mass. Thus, the radial excitations (2850) and
(2740) are predicted, both with a width of about 50 MeV. The former
state appears to correspond to the new (2860) resonance decaying to
announced by BABAR in the course of this work. Also the (2400)
resonance is roughly reproduced, though perhaps with a somewhat too low central
resonance peak.Comment: Plain LaTeX, 4 pages, 2 Postscript figures; v2: REVTeX, 4 pages,
introduction expanded, "Note added in proof" and references added, figures
with more detail and improved quality, version accepted for publication in
Physical Review Letter
Recoupling matrix elements and decay
Recoupling matrix elements are evaluated, in the harmonic oscillator
approximation, for all possible angular and radial excitations in processes
where quarks recombine. A diagrammatic representation is given. Their use is
demonstrated in calculating the transition potential for rho to two pions in a
pair creation model.Comment: 15 pages, 10 figure
The complex relation between production and scattering amplitudes
The unitarity relation, Im(A)=T* A, is derived for a three-body production
amplitude, A, that consists of a complex linear combination of elements of the
two-body scattering amplitude, T. We conclude that the unitarity relation does
not impose a realness condition on the coefficients in the expansion of, A, in
terms of, T.Comment: 4 pages plain LaTe
Continuum bound states K-long, D_{1}(2420), D_{s1}(2536) and their partners K-short, D_{1}(2400), D*_{sJ}(2463)
The very recently observed meson is described as a
bound state in a unitarised meson model, owing its
existence to the strong OZI-allowed coupling to the nearby -wave
threshold. By the same non-perturbative mechanism, the narrow
axial-vector resonance shows up as a quasi-bound-state partner
embedded in the continuum. With the same model and parameters, it
is also shown that the preliminary broad resonance and
the established narrow may be similar
partners, as a result of the strong OZI-allowed coupling to the
nearby -wave threshold. The continuum bound states
(2420) and are found to be mixtures of 33%
and 67% , whereas their partners and
have more or less the opposite -state
content, but additionally with some or admixture,
respectively.
The employed mechanism also reproduces the ratio of the - mass
difference and the width, by describing as a bound state
embedded in the continuum. The model's results for
states containing one quark are also discussed.Comment: 11 pages, plain LaTeX, v2:relation to work of Kokoski and Godfrey in
conclusions and more references v3:B-states included. More reference
Production of hadron pairs in electron-positron annihilation near the K(+)K(-), D-Dbar, B-Bbar and Lambda(c)(+)-Lambda(c)(-) thresholds
We study the structures in cross sections and R ratios concerning
electron-positron annihilation reactions, for open-strangeness, open-charm and
open-beauty hadron-pair production, from the perspective of a recently
developed production formalism. Special attention is paid to non-resonant
contributions. Known, tentative, and yet unknown resonances are spotted, with
estimates for their masses and widths.Comment: regular LaTeX, 17 pages, 12 figure
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