Σ0Lifetime and Associated Photoproduction Poles

The Born-approximation calculations for the differential cross sections for the photoproduction of $K^{+}-\Lambda$ and $K^{+}-{\Sigma }^0$ pairs from hydrogen are generalized to include the effect of the $\Sigma -\Lambda$ mass difference and the possibility of odd $\Sigma -\Lambda$ parity. The residues of the poles in the unphysical regions of the center-of-mass production angle are computed. It is shown that if the laboratory photon energy is greater than about 2 Bev, one could obtain information about the ${\Sigma }^0$ lifetime and the anomalous moment of the produced hyperon by extrapolating the experimentally measured differential cross section in the backward direction of the $K$-production angle.