446 research outputs found
Production in Proton-Proton Collisions near Threshold
Within the one-pion exchange model we calculate the near-threshold
production from collisions including the final state
interaction between the protons. Since the description of the data is quite
well we conclude that or exchange currents either play
no role or cancel each other to a large extent in this reaction.Comment: 7 pages, LaTeX, including 3 ps-figures, UGI-98-20. To be pub. EPJ-
On the current status of OZI violation in and pp reactions
The available data on and production from and
collisions are reanalyzed with respect to an OZI rule violation on the basis of
transition matrix elements. The data are found to be compatible with a constant
ratio up to excess energies MeV, however, the ratio
deviates substantially from the SU(3) prediction based on the present
knowledge of the mixing angle.Comment: 6 pages, svjour-style, including 10 ps-figure
Strangeness production from collisions in nuclear matter
Kaon production in pion-nucleon collisions in nuclear matter is studied in
the resonance model. To evaluate the in-medium modification of the reaction
amplitude as a function of the baryonic density we introduce relativistic,
mean-field potentials for the initial, final and intermediate mesonic and
baryonic states. These vector and scalar potentials were calculated using the
quark-meson coupling (QMC) model. The in-medium kaon production cross sections
in pion-nucleon interactions for reaction channels with and
hyperons in the final state were calculated at the baryonic densities
appropriate to relativistic heavy ion collisions. Contrary to earlier work
which has not allowed for the change of the cross section in medium, we find
that the data for kaon production are consistent with a repulsive -nucleus
potential.Comment: Revtex, 13 pages, 12 Postscript figures. A new secion for the
resonance model has been added (with 2 new postscript figures). Version to
appear in Phys. Rev.
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