Measurement of γp→K+Λ and γp→K+Σ0 at photon energies up to 2 GeV

Strangeness production on the nucleon

“…The data are from Ref. [23]. scattering [53], can be understood in terms of values for g K + Λp and g K + Σ 0 p which are in good agreement with the SU(3) predictions.…”

“…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.…”

“…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].…”

Photoproduction for N* and Related Topics at LEPS/LEPS2

“…Since only πN channel has been extensively studied so far, N * studies using other channels are very important. In 1999, Mart and Bennhold [6] pointed out that one of the missing resonances was observed in the total cross sections for the γ p → K + Λ reaction measured by SAPHIR collaboration [7]. This observation triggered advanced N * studies using various reactions.…”