On the determination of the parity of the $Θ^+$

Abstract

We critically examine the possibility of determining the parity of the $Θ^+(1540)$ from the reactions $NN\to Θ^+Y$ ($Y$ = $Λ$, $Σ$) recently discussed in the literature. Specifically, we study the energy dependence of those observables that were suggested to be the most promising ones to unravel the parity of the $Θ^+$, namely the spin correlation coefficient $A_{xx}$, and the spin transfer coefficient $D_{xx}$. We show that the energy dependence of $σ_0(1+A_{xx})$, corresponding to the spin-triplet production cross section, guarantees unambiguous information on the parity of the $Θ^+$. Here, $σ_0$ denotes the unpolarized cross section. Also, the possibility to determine the parity of the $Θ^+$ through the energy dependence of $σ_0D_{xx}$ is discussed.