Tübingen 2003 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 30: Elektromagnetische und hadronische Proben V
HK 30.7: Vortrag
Mittwoch, 19. März 2003, 15:45–16:00, B
Strangeness production near threshold in pp-collisions — •P. Winter — Institut für Kernphysik, Forschungszentrum Jülich, 52425 Jülich
Motivated by the ongoing discussion concerning the nature of the scalar resonances f0(980) and a0(980), the COSY-11 [1] collaboration has taken exclusive data on the pp→ pp K+K− reaction near the production threshold. A first total cross section σ=1.80±0.27−0.35+0.28 for the excess energy Q=17 MeV has been determined including statistical and systematical errors [2].
In contrary to the η, ω and η′ production, the cross section values obtained at COSY-11 [2] and DISTO [3] are in good agreement with one-meson exchange calculations neglecting final state interaction (FSI) effects. The absence of the FSI is not yet understood and might be explained by either a compensation of the strong pp interaction through a pK− FSI effect or due to an additional degree of freedom caused by the four-body final state. In the latter case, strong FSI effects can be expected at Q-values very close to the K+K− production threshold [4]. Therefore, data at the excess energies Q=10 and 17 MeV have been taken at COSY-11 and the status of the current analysis will be presented and discussed.
[1] S. Brauksiepe et al., Nucl. Instr. & Meth. A 376 (1996) 397.
[2] C. Quentmeier et al., Phys. Lett. B 515 (2001) 276.
[3] F. Balestra et al., Phys. Rev. C 63 (2001) 024004.
[4] A. Sibirtsev, Publ. of Research Centre Jülich: Matter and Materials 11 (2002) 239.