A QUARK-MODEL OF (LAMBDA)OVER-BAR-LAMBDA PRODUCTION IN (P)OVER-BAR-P INTERACTIONS

A quark model that includes both scalar and vector contributions to th e reaction mechanism (SV quark model) is used in a DWBA calculation of the LAMBDALAMBDABAR production in pp-interactions. Total and differen tial cross sections, polarizations, depolarizations, and spin-correlat ion coefficients are computed for laboratory momenta from the threshol d to 1695 MeV/c. The free parameters of the calculation are the scalar and vector strengths, a quark-cluster size parameter, and the paramet ers of the unknown LAMBDALAMBDABAR potentials. Good agreement with exp eriment is found for constructive interference of the scalar and vecto r terms and for AA potentials that differ from those suggested by seve ral authors on the basis of SU(3) arguments. The fit to the data is be tter than that obtained by other quark models, which use only scalar o r vector annihilation terms. The agreement with the experiment is also better than that found in meson-exchange models. The recent suggestio n [1] that measurement of the depolarization parameter D(nn) can be us ed to discriminate between meson-exchange and quark models is examined in detail. We conclude that a measurement of D(nn) will provide a tes t to find which of these models, as presently constructed, is the more appropriate description of strangeness production in the ppBAR --> LA MBDALAMDABAR reaction.