Measurement of γp→K0Σ+ at photon energies up to 1.55 GeV

K-Λ and K-Σ photo-production in a coupled channels framework

“…6. For the dashed line the ρ-meson t-channel contribution to the different matrix elements for the kaon states is switched off, which enhances the cross section in K 0 Σ + [32,33] and new [11,12] data for angle integrated cross sections from the SAPHIR Collaboration.…”

Strangeness production on the nucleon

“…In a second step, these values can be compared to quark model predictions [2,4,5,42], although the effects of final state interactions, which are expected to be partly absorbed in the effective couplings, may somehow obscure the results. Throughout this work, we will compare our model predictions to the SAPHIR data base [23,24] to determine the vertex couplings. When performing a global fit to N data points, the optimum set of coupling constants is the one that produces the lowest value for χ 2 , which is defined in the standard manner:…”

“…This feature is usually interpreted in terms of kaon and K * exchange in the t-channel. However, for some photon energies one discerns in both the K + Λ and the K + Σ 0 channel, differential cross sections which steeply rise as one moves out of the forward direction, reach their maximum and fall off again as more backward angles are probed [23,24,55]. The peak of the angular cross section does not coincide with exactly zero degrees and one experiences a short rise as one moves out of the very forward direction.…”

“…In dit werk werd veel aandacht besteed aan het bepalen van de dominante resonantiebijdragen in de verschillende vreemdheidsproductie reacties. In het K + Λ kanaal werd vastgesteld dat de vier nucleonre-sonanties S 11 (1650), P 11 (1710), P 13 (1720) en D 13 (1895) een belangrijke rol spelen in de reactiedynamica en in staat zijn om de recente SAPHIR data [23,24] goed te beschrijven. In de KΣ reacties werden drie nucleonresonanties (S 11 (1650), P 11 (1710), P 13 (1720)) en twee ∆ * toestanden (S 31 (1900) en P 31 (1910)) geïdentificeerd als dominante intermediaire deeltjes.…”

“…To make matters even worse, the accuracy of the measurements suffered from the very low counting rates, reflecting cross sections of the order of microbarns, compared to for example π photoproduction which are characterized by cross sections in the milibarn range. One had to wait until 1998, when the SAPHIR collaboration at Bonn [23,24] released the first extensive and accurate database for all three γp → K + Λ, K + Σ 0 and K 0 Σ + reactions. The results of this experiment clearly triggered renewed interest at various theoretical groups [25][26][27][28][29][30][31][32].…”