We measured the polarization of 51 195 ${\Lambda }^0$'s produced in the specific reaction $\mathrm{pp}\to p{\Lambda }^0{K}^{+}{\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$ with 27.5 GeV/c protons incident on a liquid hydrogen target. Because the reaction was measured completely, the polarization was studied versus the following: $x_F(-1\mathrm{}\mathrm{to}+1\mathrm{})$, ${\Lambda }^0$ transverse momentum (0 to 1.32 GeV/c), correlations with the momentum vectors of the other particles in the reaction, and the invariant mass of combinations of particles in the final state. The dependence of the polarization on these variables does not always agree with theoretical expectations.

• Received 11 September 1995

DOI:https://doi.org/10.1103/PhysRevLett.76.22