Scaling and Resonances in Elementary K+Λ Photoproduction

Recent cross-section data for the reaction γ+p→K++Λ are examined for evidence of scaling in both the low-t Regge domain and in the high-s√ and −tdomain where constituent counting may apply. It is shown that the reaction does scale in both regimes. At large center-of-mass angles, s−7 scaling appears to hold at essentially all −t but with angle-dependent oscillations. The scaled data show particularly strong evidence for s-channel resonances for −t below 2 GeV2 and for W below about 2.3 GeV. The dominant contributions are consistent with an N∗S11 resonance at 1690 MeV, a P13 resonance at 1920 MeV, and a D13 resonance at 2100 MeV, which interfere to give the observed strong angular dependence.