E- and it- POLARIZATION FROM A NEUTRAL HYPERON BEAM

The lack of understanding of the origin of hyperon polarization is a problem in high energy physics which remains nearly 20 years after its discovery 1. Several phenomenological models exist 2-5 but their predictions are for the most part qualitative or semi-quantitative. Possible meehvatisms for hyperon polarization vary. In the DeGrand-Miettinen model 2, polaxization results from Thomas precession of the quark spins in the recombination process. In the Lund model s, polarized s~ pairs are produced by stretching of a color field and conservation of angular momentum leads to a preferred spin direction. There are also several Regge type models 4,s in which polarization effects arise from interference between different production channels. More recent data e-s taken to gain additional insight has, if anything, created additional confusion. For example, A's and f~-'s produced by protons are unpolarized while -~+'s and ~Y-'s are produced with sizeable polarization. Additional data is clearly needed to untangle this picture. With this in mind we present recent results from Fermilab experiment E-800 on the polarization of .=.and f~produced from polarized and unpolarized neutral hyperon beams. Little data exists on the polarization of hyperons produced from strange baryon beams such as is presented here. A simple model borrowing heavily from the DeGrand-Miettinen model 2 can be invoked to understand some features of the hyperon polarization data. Working with SU(6) wavefunctions and the quark recombination model, we assume a sufficient condition for hyperon polarization occurs when there are quarks in common between beam and target particles and when at least one s quark is picked from the sea in the recombination process. This simple model when applied to proton production "predicts" opposite signs for A, T.-, and E ~ polarization compared to ~+, E, and 5-2.o polarization. The model however says nothing about the PT or ZF dependence of the polarization, anti-hyperon polarization, K ---, A polarization, etc.