Bochum 1998 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HK: Hadronen und Kerne
HK 58: Plenar
HK 58.2: Gruppenbericht
Donnerstag, 19. März 1998, 12:00–12:30, P
Strangeness Production in the Reaction p p → K+ Λ p Close to Threshold* — •W. Eyrich — Physikalisches Institut, Universität Erlangen-Nürnberg, Erwin-Rommel-Str. 1, D-91058 Erlangen
The investigation of the associated strangeness production in elementary reactions like p p → K Y N should give information concerning the manifestation of QCD in the nonperturbative regime going a step beyond low energy pion physics. The global interest in these processes is the ss-creation and its description in models, based especially on mesonic and effective quark-gluon degrees of freedom. Of special interest studying strangeness production is the possible ss-content of the nucleon, by which the observables are expected to be influenced significantly. Moreover, the data of strangeness production in the nucleon-nucleon system in the threshold region are of great interest as an input to describe strangeness production in nucleon-nucleus and nucleus-nucleus systems.
In the present contribution we report on the exclusive measurement of the reaction channel p p → K+ Λ p using the time-of-flight spectrometer TOF at COSY at beam momenta of 2.50 GeV/c and 2.75 GeV/c, respectively. The concept of the experiment is the complete reconstruction of the p p → K+ Λ p events including the delayed decay Λ → π− p, which gives a clear signature for the events of interest. Covering the full phase space of the primary reaction products by the detector we are able to extract all differential distributions and the total cross section model independently.
The angular and momentum distributions show a smooth behavior in rough agreement with the phase space. The Λ polarization as a function of its transversal momentum was deduced to be negative for transverse momentum transfer pT ≥ 0.3 GeV/c. The results obtained for the total cross section are confronted with existing data and compared with phenomenological parametrizations and model calculations on the basis of meson exchange.
An outlook to the further experimental program on assoziated strangeness production at COSY-TOF will be given.
* supported by German BMBF and Forschungszentrum Jülich