The role of vector-baryon channels and resonances in the gamma p to K0 Sigma+ and gamma n to K0 Sigma0 reactions near the K* Lambda threshold

Abstract

We have studied the γp→K0Σ+γp→K0Σ+ reaction in the energy region around the K⁎ΛK⁎Λ and K⁎ΣK⁎Σ thresholds, where the CBELSA/TAPS cross section shows a sudden drop and the differential cross section experiences a transition from a forward-peaked distribution to a flat one. Our coupled-channel model incorporates the dynamics of the vector meson-baryon interaction which is obtained from the hidden gauge formalism. We find that the cross section in this energy region results from a delicate interference between amplitudes having K⁎ΛK⁎Λ and K⁎ΣK⁎Σ intermediate states. The sharp downfall is dictated by the presence of a nearby N⁎N⁎ resonance produced by our model, a feature that we have employed to predict its properties. We also show results for the complementary γn→K0Σ0γn→K0Σ0 reaction, the measurement of which would test the mechanism proposed in this work.