Spin observables and the determination of the parity of ${\Theta }^{+}$ in photoproduction reactions

Abstract

Spin observables in the photoproduction of the ${\Theta }^{+}$ are explored for the purpose of determining the parity of the ${\Theta }^{+}$. Based on reflection symmetry in the scattering plane, we show that certain spin observables in the photoproduction of the ${\Theta }^{+}$ can be related directly to its parity. We also show that measurements of both the target nucleon asymmetry and the polarization may be useful in determining the parity of ${\Theta }^{+}$ in a model-independent way. Furthermore, we show that no combination of spin observables involving only the polarization of the photon and/or nucleon in the initial state can determine the parity of ${\Theta }^{+}$ unambiguously.

Comments: LaTeX, 11 pages, minor revision