https://doi.org/10.1140/epja/i2002-10234-2
Associated strangeness production at threshold
1
IKP, Forschungszentrum Jülich, D-52425, Jülich, Germany
2
Institute of Physics, University of Silesia, PL-40-007, Katowice, Poland
3
IKP, D-48149, Münster, Germany
4
Institute of Physics, Jagellonian University, PL-30-059, Kraków, Poland
5
Institute of Nuclear Physics, PL-31-342, Kraków, Poland
6
ZEL, Forschungszentrum Jülich, D-52425, Jülich, Germany
* e-mail: P.Kowina@fz-juelich.de
The associated strangeness dissociation at threshold has been studied at the COSY-11 facility measuring the hyperon and the K
+
K
- meson pair production. Measurements of the near-threshold 
and 
production via the 
reaction (S. Sewerinet al., Phys. Rev. Lett. 83, 682 (1999)) at COSY-11 have shown that the 
cross-section ratio exceeds the value at high excess energies (
MeV (A. Baldiniet al., Total Cross-Sections for Reactions of High-Energy Particles, Landolt-Börnstein, New Series, Vol. I/12 (Springer, Berlin, 1988))) by an order of magnitude. For a better understanding additional data have been taken between 13 MeV and 60 MeV excess energy. The near-threshold production of the charged kaon-antikaon pair is related to the discussion about the nature of the scalar states in the 1 GeV/c
2 mass range, i.e. the f
0(980) and a
0(980) (O. Krehl, R. Rapp, J. Speth, Phys. Lett. B 390, 23 (1997)). The interpretation as a 
molecule is strongly dependent on the K-
interaction which can be studied via the production channel. A first total cross-section value on the reaction 
at an excess energy of 17 MeV (C. Quentmeieret al., Phys. Lett. B 515, 276 (2001)), i.e. below the 
production threshold, was measured.
© Società Italiana di Fisica and Springer-Verlag, 2003
