92 research outputs found
S-wave and P-wave non-strange baryons in the potential model of QCD
In this paper, we study the nucleon energy spectrum in the ground-state (with
orbital momentum L=0) and the first excited state (L=1). The aim of this study
is to find the mass and mixing angles of excited nucleons using a potential
model describing QCD. This potential is of the "Coulombian + linear" type and
we take into account some relativistic effects, namely we use essentially a
relativistic kinematic necessary for studying light flavors. By this model, we
found the proton and masses respectively equal to (,
), and the masses of the excited states are between and
.Comment: 26 pages, 1 figur
The decay of the observed (1400) and (1600) hybrid candidates
We study the possible interpretation of the two exotic resonances at 1400 and 1600 MeV, claimed to be observed by BNL, decaying
respectively into , , and . These
objects are interpreted as hybrid mesons, in the quark-gluon constituent model
using a chromoharmonic confining potentiel.
The quantum numbers can be considered in a
constituent model as an hybrid meson (). The lowest states may be built in two ways : =1 (gluon-excited)
corresponding to an angular momentum between the gluon and () system,
while (quarks-excited) corresponds to an angular momentum
between and . For the gluon-excited mode hybrids, we find
the decay dominated by the channel, and by the channel
for the quark-excited mode. In our model, neither the quark-excited nor the
gluon-excited (1400 MeV) hybrids can decay into and
, in contradiction with experiment. Hence, the 1400 MeV resonance
seems unlikely to be an hybrid state. The (1600 MeV) gluon-excited
hybrid is predicted with too large a total decay width, to be considered as an
hybrid candidate. On the contrary the quark-excited mode has a total decay
width around 165 MeV, with a preferred decay channel, in agreement
with BNL. Our conclusion is that {\it{this resonance may be considered as a
hybrid meson in the quark-excited mode}}Comment: 13 pages, 1 figur
(Field) Symmetrization Selection Rules
QCD and QED exhibit an infinite set of three-point Green's functions that
contain only OZI rule violating contributions, and (for QCD) are subleading in
the large N_c expansion. The Green's functions describe the ``decay'' of a
J^{PC}={1,3,5 ...}^{-+} exotic hybrid meson current to two J=0 (hybrid) meson
currents with identical P and C. We prove that the QCD amplitude for a neutral
hybrid {1,3,5 ...}^{-+} exotic current to create eta pi0 only comes from OZI
rule violating contributions under certain conditions, and is subleading in
N_c.Comment: 20 pages, LaTeX. Two postscript figures. Final published versio
Hybrid States from Constituent Glue Model
The hybrid meson is one of the most interesting new hadron specie beyond the
naive quark model. It acquire a great attention both from the theoretical and
experimental efforts. Many good candidates have been claimed to be observed,
but there is no absolute confirmation about existence of hybrid mesons. In the
present work we propose new calculations of the masses and decay widths of the
hybrid mesons in the context of constituent gluon model.Comment: 19 pages, 11 Table
Decays of the Exotic Hybrid and - Mixing
QCD sum-rules are used to calculate the decay widths of the exotic hybrid in two different
mixing schemes.
In the conventional flavour octet-singlet mixing scheme, the decay widths are
both found to be small, while in the recently-proposed quark mixing scheme, the
decay width is large compared with
the decay width . These
results provide some insight into - mixing and hybrid decay
features.Comment: latex2e, 11 pages with 4 embedded eps figures. v 2 corrects reference
[5] and minor error in equation (11
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