436 research outputs found
Modular classes of Poisson-Nijenhuis Lie algebroids
The modular vector field of a Poisson-Nijenhuis Lie algebroid is defined
and we prove that, in case of non-degeneracy, this vector field defines a
hierarchy of bi-Hamiltonian -vector fields. This hierarchy covers an
integrable hierarchy on the base manifold, which may not have a
Poisson-Nijenhuis structure.Comment: To appear in Letters in Mathematical Physic
A supergeometric approach to Poisson reduction
This work introduces a unified approach to the reduction of Poisson manifolds
using their description by graded symplectic manifolds. This yields a
generalization of the classical Poisson reduction by distributions
(Marsden-Ratiu reduction). Further it allows one to construct actions of strict
Lie 2-groups and to describe the corresponding reductions.Comment: 40 pages. Final version accepted for publicatio
Role of Scalar Meson Resonances in $K_{L}^{0} \rightarrow \pi^{0} \gamma \gamma Decay
Corrections to decay induced by
scalar meson exchange are studied within chiral perturbation theory. In spite
of bad knowledge of scalar-mesons parameters, the calculated branching ratio
can be changed by a few percent.Comment: 18 pages of text, 2 figures (available upon request); preprint
IJS-TP-16-94 , TUM-T31-63-94
Insight into the Scalar Mesons from a Lattice Calculation
We study the possibility that the light scalar mesons are (qbar qbar q q)
states rather than (qbar q). We perform a lattice QCD calculation of
pseudoscalar meson scattering amplitudes, ignoring quark loops and quark
annihilation, and find indications that for sufficiently heavy quarks there is
a stable four-quark bound state with J^{PC}=0^{++} and non-exotic flavor
quantum numbers.Comment: 16 pages, revtex, with eps figure
Kaon-Nucleon Scattering Amplitudes and Z-Enhancements from Quark Born Diagrams
We derive closed form kaon-nucleon scattering amplitudes using the ``quark
Born diagram" formalism, which describes the scattering as a single interaction
(here the OGE spin-spin term) followed by quark line rearrangement. The low
energy I=0 and I=1 S-wave KN phase shifts are in reasonably good agreement with
experiment given conventional quark model parameters. For Gev
however the I=1 elastic phase shift is larger than predicted by Gaussian
wavefunctions, and we suggest possible reasons for this discrepancy. Equivalent
low energy KN potentials for S-wave scattering are also derived. Finally we
consider OGE forces in the related channels K, KN and K,
and determine which have attractive interactions and might therefore exhibit
strong threshold enhancements or ``Z-molecule" meson-baryon bound states.
We find that the minimum-spin, minimum-isospin channels and two additional
K channels are most conducive to the formation of bound states.
Related interesting topics for future experimental and theoretical studies of
KN interactions are also discussed.Comment: 34 pages, figures available from the authors, revte
Radiative Scalar Meson Decays in the Light-Front Quark Model
We construct a relativistic wavefunction for scalar mesons within the
framework of light-front quark model(LFQM). This scalar wavefunction is used to
perform relativistic calculations of absolute widths for the radiative decay
processes, and
which incorporate the effects of glueball-
mixing. The mixed physical states are assumed to be ,and
for which the flavor-glue content is taken from the mixing
calculations of other works. Since experimental data for these processes are
poor, our results are compared with those of a recent non-relativistic model
calculation. We find that while the relativistic corrections introduced by the
LFQM reduce the magnitudes of the decay widths by 50-70%, the relative
strengths between different decay processes are fairly well preserved. We also
calculate decay widths for the processes and
(0^{++})\to\gamma\gamm involving the light scalars and
to test the simple model of these mesons. Our results of
model for these processes are not quite consistent with well-established data,
further supporting the idea that and are not conventional
states.Comment: 10 pages, 4 figure
Glueball spectrum based on a rigorous three-dimensional relativistic equation for two-gluon bound states I: Derivation of the relativistic equation
A rigorous three-dimensional relativistic equation satisfied by two-gluon
bound states is derived from the QCD with massive gluons. With the gluon fields
and the quark fields being expanded in terms of the gluon multipole fields and
the spherical Dirac spinors respectively, the equation is well established in
the angular momentum representation and hence is much convenient for solving
the problem of two-gluon glueball spectra. In particular, the interaction
kernel in the equation is exactly derived and given a closed expression which
includes all the interactions taking place in the two-gluon glueballs. The
kernel contains only a few types of Green's functions and commutators.
Therefore, it is not only easily calculated by the perturbation method, but
also provides a suitable basis for nonperturbative investigations
Glueball spectrum based on a rigorous three-dimensional relativistic equation for two-gluon bound states II: calculation of the glueball spectrum
In the preceding paper, a rigorous three-dimensional relativistic equation
for two-gluon bound states was derived from the QCD with massive gluons and
represented in the angular momentum representation. In order to apply this
equation to calculate the glueball spectrum, in this paper, the equation is
recast in an equivalent three-dimensional relativistic equation satisfied by
the two-gluon positive energy state amplitude. The interaction Hamiltonian in
the equation is exactly derived and expressed as a perturbative series. The
first term in the series describes the one-gluon exchange interaction which
includes fully the retardation effect in it. This term plus the linear
confining potential are chosen to be the interaction Hamiltonian and employed
in the practical calculation. With the integrals containing three and four
spherical Bessel functions in the QCD vertices being analytically calculated,
the interaction Hamiltonian is given an explicit expression in the angular
momentum representation. Numerically solving the relativistic equation with
taking the contributions arising from the retardation effect and the
longitudinal mode of gluon fields into account, a set of masses for the
and glueball states are
obtained and are in fairly good agreement with the predictions given by the
lattice simulatio
THE INTERPLAY OF THE K+K- ATOM AND THE f_0(975) RESONANCE
We predict that production of the K+K- atom in pd-3^HeX and similar reactions
exhibits a drastic missing mass spectrum due to the interplay with f_0(975)
resonance. We point out that high precision studies of the K+K- atom may shed a
new light on the nature of f_0(975).Comment: 13 page
Evidence for two-quark content of in exclusive decays
Inspired by a large decay branching ratio (BR) of
measured by Belle recently, we propose that a significant evidence of the
component of in could be
demonstrated in exclusive decays by the observation of in
the final states and . We predict the BRs of to be () while
the unknown wave functions of () are chosen to fit the
observed decays of .Comment: 4 pages, 2 figures, Revtex4, version to appear in PR
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