How to measure the parity of the Θ+\Theta^+ in p⃗p⃗\vec p\vec p collisions

Triggered by a recent paper by Thomas, Hicks and Hosaka, we investigate which observables can be used to determine the parity of the $\Theta^+$ from the reaction $\vec p\vec p \to \Sigma^+\Theta^+$ near its production threshold. In particular, we show that the sign of the spin correlation coefficient $A_{xx}$ for small excess energies yields the negative of the parity of the $\Theta^+$. The argument relies solely on the Pauli principle and parity conservation and is therefore model--independent.Comment: References completed, discussion on possible influence of background added; conclusions unchange

Strangeness Production in pp and pn Reactions at COSY

The COoler SYnchrotron COSY-J\"ulich delivers phase-space cooled, polarized proton and deuteron beams with momenta up to p=3.65 GeV/c. Various experiments on hadron-induced strangeness production on proton, neutron and nuclear targets have been carried out. Here we report about recent results on associated strangeness production in pp -> KYN (Y= Lambda,Sigma) reactions, on K^+ production in pn collisions, and on K K-bar pair production in pp interactions. We also briefly discuss possible measurements to disentangle the parity of the recently discovered pentaquark state Theta^+, the spin dependence of the YN interaction, as well as planned experiments which aim at the determination of the a_0-f_0 mixing matrix element, a quantity which is believed to be sensitive to the nature of the light scalar mesons a_0/f_0(980).Comment: 10 pages, 3 figures; Proc. VIII Int. Conf. on Hypernuclear and Strange Particle Physics, JLab, Oct. 14 - 18, 200