491 research outputs found
Omega photoproduction
Photoproduction of omega-meson is analyzed within meson exchange model and
Regge model and compared to rho-meson photoproduction. An interplay between two
models and uncertainties in data reproduction are discussed.Comment: Presented at Meson 2002, 7th Int. Workshop on Production, Properties
and Interaction of Mesons, Cracow, Poland, May 24-28 200
Lifetime of Kaonium
The kaon--antikaon system is studied in both the atomic and the strongly
interacting sector. We discuss the influence of the structures of the
and the mesons on the lifetime of kaonium. The strong
interactions are generated by vector meson exchange within the framework of the
standard invariant effective Lagrangian. In the atomic
sector, the energy levels and decay widths of kaonium are determined by an
eigenvalue equation of the Kudryavtsev--Popov type, with the strong interaction
effects entering through the complex scattering length for scattering
and annihilation. The presence of two scalar mesons, and ,
leads to a ground state energy for the kaonium atom that is shifted above the
point Coulomb value by a few hundred eV. The effect on the lifetime for the
kaonium decay into two pions is much more dramatic. This lifetime is reduced by
two orders of magnitude from sec for annihilation in a
pure Coulomb field down to sec when the strong
interactions are included. The analysis of the two photon decay width of the
suggests a generalization of the molecular picture which reduces the
lifetime of kaonium still further to .Comment: 33 pages, 12 figures;3 new figures and new comment concerning the a
Kaon-Deuteron Scattering at Low Energies
We review the experimental information on the K^+d reaction for K-meson
momenta below 800 MeV/c. The data are analysed within the single scattering
impulse approximation -- utilizing the Juelich kaon-nucleon model -- that
allows to take into account effects due to the Fermi motion of the nucleons in
the deuteron and the final three-body kinematics for the break-up and charge
exchange reaction. We discuss the consistency between the data available for
the K^+d -> K^+np, K^+d -> K^0pp and K^+d -> K^+d reactions and the
calculations based on the spectator model formalism.Comment: 26 pages, 10 figures, to appear in J. Phys.
Pion photoproduction in a dynamical coupled-channel model
Pion photoproduction reactions are investigated in a dynamical
coupled-channel approach based on the Juelich pi-N model, which presently
includes the hadronic pi-N and eta-N stable channels as well as the pi-Delta,
sigma-N and rho-N effective channels. This model has been quite successful in
the description of pi-N to pi-N scattering for center-of-mass energies up to
1.9 GeV. The full pion photoproduction amplitude is constructed to satisfy the
generalized Ward-Takahashi identity and hence, it is fully gauge invariant. The
calculated differential cross sections and photon spin asymmetries up to 1.65
GeV center-of-mass energy for the reactions gamma p to pi+ n, gamma p to pi0 p
and gamma n to pi- p are in good agreement with the experimental data.Comment: Invited talk given at 12th International Conference on Meson-Nucleon
Physics and the Structure of the Nucleon (MENU2010), Williamsburg, USA, May
31-June 4 201
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