Spin asymmetries in gamma + N --> K*bar + Theta^+

Abstract

The photoproduction processes of the exotic $Θ^+(1540)$ baryon and the $\bar{K}^*$ meson from the nucleon targets, i.e., $γn \to K^{*-} Θ^+$ and $γp \to \bar{K}^{*0} Θ^+$, are investigated in a hadronic model. We consider $K$ and $K^*$ exchanges as well as the $s$ and $u$ channel nucleon and $Θ$ terms. Various spin asymmetries together with cross sections are first computed in order to study the production mechanisms and the parity of the $Θ^+(1540)$ baryon. Within the uncertainties arising from the model-dependence of the production mechanisms and several coupling constants, we find that some target-recoil double spin asymmetries, $C^{\rm TR}_{xx'}$ and $C^{\rm TR}_{xz'}$, are sensitive to the parity of $Θ^+$. In addition, the parity asymmetry of this reaction on the neutron target, which can be obtained by analyzing $K^*$ decay distribution, is found to be useful to estimate the $K^* N Θ$ coupling.