Scaling and Resonances in Elementary K+ Lambda Photoproduction
Abstract
Recent cross section data for the reaction gamma + p K+ + Lambda are examined for evidence of scaling in both the low-t Regge domain and in the high s and -t domain 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 at 1920 MeV, and a D13 resonance at 2100 MeV, which interfere to give the observed strong angular dependence.
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