Photoproduction of ${\gamma p\to K^+\Lambda^*(1520)}$ and decay of $\Lambda^*(1520)\to K^- p$ in the Reggeized framework

Abstract

Photoproduction of the $\Lambda^*(1520)$ resonance of spin-parity ${3\over2}^-$ off the proton target is investigated within the Regge framework where the $t$-channel reggeization is applied for the $K(494)+K^*(892)+K_2^*(1430)$ exchanges in the Born amplitude. The present model is based on the two basic ingredients; the one is the minimal gauge prescription for the convergence of the reaction and the other is the role of the $K_2^*$ crucial to be consistent with high energy data. The cross sections for the total, differential and photon polarization asymmetry are reproduced without fit parameters and compared with existing data. The LAMP2 and LEPS measurements of the angular distribution of the $K^-$ in the $\Lambda^*(1520)\to K^-p$ decay are investigated and found to be dominated by the decay of $\Lambda^*$ with helicity $\pm3/2$ based on the analysis of the density matrix elements related. Detailed discussion on the density matrix elements is given to clarify the analysis of the observable. The reaction mechanism is featured by the dominance of the contact term with the $K$ and $K_2^*$ exchanges following in the low energy region. The $K^*$ exchange appears in minor role. At high energies beyond $E_\gamma\approx 5$ GeV the role of $K_2^*$ exchange leads over other exchanges in the reaction process.