Analysis and Model of Low-EnergyΛK0Production

Abstract

The low-energy $\Lambda K^0$ production data are analyzed under the assumption of a $K^{*}$-exchange background. A new interesting result is found; namely, that the observed anomaly in the polarization and slight shoulder in the cross section at 829 MeV is apparently due to a narrow $F_{\frac{5}{2}}$ resonance located at 1647 MeV. The parameters of this resonance are determined from the data by adding its contribution to a model proposed previously by the author, which gave fairly good results above and below the energy of the anomaly, after modifying the contribution from a $P_{\frac{1}{2}}$ resonance included in that model by taking into account the proper threshold behavior. Fits to all the data up to 1.03 BeV/c (900 MeV) (the region of validity of the previous model) are given. The result obtained for the product of relative partial widths agrees remarkably well with that predicted by unitary symmetry for a member of an octet with an asymmetry parameter of 0.674 (Carruther's model). It is also found that the $P_{\frac{1}{2}}$ resonance (if it exists) cannot be a member of an octet, but it has to belong to either a $\overline{1}\overline{0}$ or 27 representation, if the $F_{\frac{5}{2}}$ resonance belongs to an octet. Experiments which might confirm or deny the existence of these resonances are suggested. Further, our method of analysis is extended to a more general type of background which includes contributions from the nucleon pole and baryon exchange terms.