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

Abstract

The photoproduction processes of the exotic $\Theta^+(1540)$ baryon and the $\bar{K}^*$ meson from the nucleon targets, i.e., $\gamma n \to K^{*-} \Theta^+$ and $\gamma p \to \bar{K}^{*0} \Theta^+$, are investigated in a hadronic model. We consider $K$ and $K^*$ exchanges as well as the $s$ and $u$ channel nucleon and $\Theta$ terms. Various spin asymmetries together with cross sections are first computed in order to study the production mechanisms and the parity of the $\Theta^+(1540)$ 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 $\Theta^+$. 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 $K^* N \Theta$ coupling.