Eur. Phys. J. A 12, 435-446 (2001)
Chiral dynamics and the reactions
and
E. Oset1, J.A. Oller2 and U.-G. Meißner2
1 Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigación de Paterna, Aptad. 22085, 46071, Valencia, Spain
2 Forschungszentrum Jülich, Institut für Kernphysik (Theorie), D-52425 Jülich, Germany
u.meissner@fz-juelich.de
(Received: 28 September 2001 Communicated by A. Schäfer)
Abstract
We perform a study of the final-state interactions of the
and the
systems in the reactions
and
. Since the two-meson system couples strongly to
the
a0(980) resonance, these reactions are expected to be an
additional source of information about the controversial scalar sector. We also
show that these reactions present peculiar features which can shed additional light
on the much debated meson-baryon scalar sector with strangeness
-1. We deduce
the general structure of the amplitudes close to
the
threshold, allowing
for primary
as well as
production with the two
mesons in relative
S- or
P-wave. The interactions of the mesons are accounted
for by using chiral unitary techniques, which generate dynamically the
a0(980) resonance, and the
interaction is also
taken into account. General formulae are derived that allow to incorporate the
final-state interactions in these systems for any model of the production
mechanism. We illustrate this approach by considering two specific production
mechanisms based on three flavor meson-baryon chiral perturbation theory. It is
demonstrated that in this scenario the
interactions are very important
and can change the cross-section by as much as one order of magnitude. The amount of
versus
production is shown to depend critically on
the primary mixture of the two mechanisms, with large interference effects due
to final-state interactions. These effects are also shown to occur in the event
distributions of invariant masses which are drastically modified by the final-state
interactions of the two-meson or the
system.
12.39.Fe - Chiral Lagrangians.
13.75.Lb - Meson-meson interactions.
13.75.Gx - Kaon-baryon interactions.
© Società Italiana di Fisica, Springer-Verlag 2001