New fit to the reactionγp→K+Σ0

Abstract

The reaction $\ensuremath{\gamma}p\ensuremath{\rightarrow}{K}^{+}{\mathrm{\ensuremath{\Sigma}}}^{0}$ has been investigated using a tree-level effective Lagrangian model similar to that employed previously by the author to study the electromagnetic production of $\mathrm{\ensuremath{\Lambda}}$'s from protons. In addition to the Born terms, the model incorporates a number of baryon resonances with spins up to $\frac{5}{2}$ and the two kaon resonances, ${K}^{\ensuremath{\star}}(892)$ and $K1(1270)$. Momentum- and energy-dependent widths for the nucleon and $\mathrm{\ensuremath{\Delta}}$ resonances are included by means of a dynamical model that makes use of empirical on-shell branching ratios. The model parameters, consisting of products of the coupling strengths at the electromagnetic and strong interaction vertices in the resonance contributions, are fit to a large pool of photoproduction data from the CLAS and GRAAL Collaborations. Results are presented for the unpolarized differential cross section, the photon beam asymmetry $\mathrm{\ensuremath{\Sigma}}$, the hyperon recoil asymmetry $P$, and the double-polarization observables ${C}_{x}$ and ${C}_{z}$ in a variety of kinematical situations and compared with the data.