Λ(1520)photoproduction off a proton target with Regge contributions

Abstract

We investigate the $\ensuremath{\Lambda}(1520,3/{2}^{\ensuremath{-}})\ensuremath{\equiv}{\ensuremath{\Lambda}}^{*}$ photoproduction off the proton target beyond the resonance region within a model including the Regge contributions, the tree-level diagrams with the nucleon and the certain resonance intermediate states, and one contact term. The Reggeized propagators for the $K$ and ${K}^{*}$ exchanges in the $t$ channel are employed in a gauge-invariant manner. We compute the angular and energy dependences of the cross section and some polarization observables, such as the photon-beam asymmetry and the polarization-transfer coefficients. Our results qualitatively agree with the current experimental data. We find that the Regge contributions are necessary to explain the high-energy data beyond ${E}_{\ensuremath{\gamma}}\ensuremath{\approx}4$ GeV, especially for the angular dependences in the forward region. On the contrary, the polarization observables are insensitive to the Regge contributions due to the contact-term dominance, which is a consequence of gauge invariance. We also calculate the ${K}^{\ensuremath{-}}$-angle distribution function in the Gottfried-Jackson frame, using the polarization-transfer coefficients in the $z$ direction. We find that it owns a complicated angle and energy dependences in the forward ${K}^{+}$ scattering region.