Contributions of box diagrams and $\hat{I}”(1940)$ resonance to $K^0\hat{I}{\pounds }^{+}$ photoproduction

Abstract

We study first the box-diagram contribution to the ${\hat{I}}^{3}p\to K^0\hat{I}{\pounds }^{+}$ process to understand the anomaly of the kaon photoproduction cross section from CBELSA/TAPS experiment at Electron Stretcher Accelerator (ELSA), where the imaginary part of the scattering amplitude from the box-diagrams is calculated by using Cutkosky's rules in the on-shell approximation while the real part of the amplitude is derived by dispersion relation calculations. Together with the results of the K-MAID model, the contribution of the box-diagrams fails to provide the sudden drop of the differential cross-section between the $K^{\ast }\hat{I}›$ and $K^{\ast }\hat{I}\pounds$ thresholds. In addition, we include the $\hat{I}”(1940)$ resonance in the process to complete the description of the differential cross-section. Combining the contributions from the K-MAID model, the box-diagrams and the $\hat{I}”(1940)$ resonance, we have obtained the theoretical differential cross-section the ${\hat{I}}^{3}p\to K^0\hat{I}{\pounds }^{+}$ process, which is compatible with the CBELSA/TAPS experimental data.

14 pages, 3 figures