Anomaly in the K^0_S Sigma^+ photoproduction cross section off the   proton at the K* threshold
  The $\gamma + p \rightarrow K^0 + \Sigma^+$ photoproduction reaction is investigated in the energy region from threshold to $E_\gamma = 2250$\,MeV. The differential cross section exhibits increasing forward-peaking with energy, but only up to the $K^*$ threshold. Beyond, it suddenly returns to a flat distribution with the forward cross section dropping by a factor of four. In the total cross section a pronounced structure is observed between the $K^*\Lambda$ and $K^*\Sigma$ thresholds. It is speculated whether this signals the turnover of the reaction mechanism from t-channel exchange below the $K^*$ production threshold to an s-channel mechanism associated with the formation of a dynamically generated $K^*$-hyperon intermediate state. 
R. Ewald, A. V. Anisovich, B. Bantes, O. Bartholomy, D. Bayadilov, R.   Beck, Y. A. Beloglazov, K.-T. Brinkmann, V. Crede, H...
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