Threshold hyperon production in proton–proton collisions at COSY-11

• DOI: 10.1016/j.physletb.2006.07.066
• Publication Date: 2006-08-11T11:09:52Z
• Authors: T. Rożek; D. Grzonka; H.-H. Adam; A. Budzanowski; R. Czyżykiewicz; M. Janusz; L. Jarczyk; B. Kamys; A. Khoukaz; K. Kilian; P. Klaja; P. Kowina; P. Moskal; W. Oelert; C. Piskor-Ignatowicz; J. Przerwa; J. Ritman; T. Sefzick; M. Siemaszko; J. Smyrski; A. Täschner; P. Winter; M. Wolke; P. Wüstner; Z. Zhang; W. Zipper
• Keywords: Sigma0: hadroproduction; signia productions; p p: exclusive reaction; Sigma+: hadroproduction; cross section: parametrization; FOS: Physical sciences; Juelich COSY PS; 01 natural sciences; COSY-11; strangeness; meson: exchange; 0103 physical sciences; threshold; near threshold hyperon production; mass spectrum: missing-mass; sigma production; Nuclear Experiment (nucl-ex); info:eu-repo/classification/ddc/530; Nuclear Experiment; channel cross section; Lambda: hadroproduction; K+: associated production; 2.60: 2.74 GeV; final-state interaction; magnetic spectrometer: experimental results; p p --> Sigma+ n K+; kaon

7 pages, 8 figures, Phys. Lett. B in print, in the second version a minor editorial changes have been made by a native speaking proofreader and a note in proof has been added with an additional reference<br/>Sigma+ hyperon production was measured at the COSY-11 spectrometer via the p p --> n K+ Sigma+ reaction at excess energies of Q = 13 MeV and Q = 60 MeV. These measurements continue systematic hyperon production studies via the p p --> p K+ Lambda/Sigma0 reactions where a strong decrease of the cross section ratio close-to-threshold was observed. In order to verify models developed for the description of the Lambda and Sigma0 production we have performed the measurement on the Sigma+ hyperon and found unexpectedly that the total cross section is by more than one order of magnitude larger than predicted by all anticipated models. After the reconstruction of the kaon and neutron four momenta, the Sigma+ is identified via the missing mass technique. Details of the method and the measurement will be given and discussed in view of theoretical models.<br/>