Covariant Model for Dynamical Quark Confinement

Based on a recent manifestly covariant time-ordered approach to the relativistic many-body problem, the quark propagator is defined by a nonlinear Dyson--Schwinger-type integral equation, with a one-gluon loop. The resulting energy-dependent quark mass is such that the propagator is singularity-free for real energies, thus ensuring confinement. The self-energy integral converges without regularization, due to the chiral limit of the quark mass itself. Moreover, the integral determines the low-energy limit of the quark-gluon coupling constant, for which a value of $g^2/4\pi =4.712$ is found.Comment: 7 pages, REVTeX; 2 figures, available from the author (by fax, or as postscript files by email

Model-independent aspects of the reaction Kˉ+N→K+Ξ\bar{K} + N \to K + \Xi

Various model-independent aspects of the $\bar{K} N \to K \Xi$ reaction are investigated, starting from the determination of the most general structure of the reaction amplitude for $\Xi$ baryons with $J^P=\frac12^\pm$ and $\frac32^\pm$ and the observables that allow a complete determination of these amplitudes. Polarization observables are constructed in terms of spin-density matrix elements. Reflection symmetry about the reaction plane is exploited, in particular, to determine the parity of the produced $\Xi$ in a model-independent way. In addition, extending the work of Biagi $\mathrm{\textit{et al. } [Z. Phys.\ C \textbf{34}, 175 (1987)]}$, a way is presented of determining simultaneously the spin and parity of the ground state of $\Xi$ baryon as well as those of the excited $\Xi$ states

Time-delay in a multi-channel formalism

We reexamine the time-delay formalism of Wigner, Eisenbud and Smith, which was developed to analyze both elastic and inelastic resonances. An error in the paper of Smith has propagated through the literature. We correct this error and show how the results of Eisenbud and Smith are related. We also comment on some recent time-delay studies, based on Smith's erroneous interpretation of the Eisenbud result.Comment: 4 pages, no figure

Covariant Model for Dynamical Quark Confinement

Based on a recent manifestly covariant time-ordered approach to the relativistic many-body problem, the quark propagator is defined by a nonlinear Dyson--Schwinger-type integral equation, with a one-gluon loop. The resulting energy-dependent quark mass is such that the propagator is singularity-free for real energies, thus ensuring confinement. The self-energy integral converges without regularization, due to the chiral limit of the quark mass itself. Moreover, the integral determines the low-energy limit of the quark-gluon coupling constant, for which a value of $g^2/4\pi =4.712$ is found.Comment: 7 pages, REVTeX; 2 figures, available from the author (by fax, or as postscript files by email