Influence of N*-resonances on hyperon production in the channel pp --> K+ Lambda p at 2.95, 3.20 and 3.30 GeV/c beam momentum

Hyperon production in the threshold region was studied in the reaction pp -> K+ Lambda p using the time-of-flight spectrometer COSY-TOF. Exclusive data, covering the full phase-space, were taken at the three different beam momenta of pbeam = 2.95, 3.20 and 3.30GeV/c, corresponding to excess energies of epsilon = 204, 285 and 316MeV, respectively. Total cross-sections were deduced for the three beam momenta to be 23.9 ± 0.8 ± 2.0 μb, 28.4 ± 1.3 ± 2.2 μb and 35.0 ± 1.3 ± 3.0 μb. Differential observables including Dalitz plots were obtained. The analysis of the Dalitz plots reveals a strong influence of the N(1650)-resonance at pbeam = 2.95GeV/c, whereas for the higher momenta an increasing relative contribution of the N(1710)- and/or of the N(1720)- resonance was observed. In addition, the p Lambda-final-state interaction turned out to have a significant influence on the Dalitz plot distribution