The ratio of the cross section for ..sigma../sup 0/ inclusive production to the cross section for ..lambda../sup 0/ inclusive production has been measured with 28.5-GeV/c protons incident on a beryllium target at an average laboratory production angle of 4/sup 0/. This ratio was measured to be 0.278 +- 0.011 +- 0.05, where the uncertainties are statistical and systematic in that order. The ratio does not depend strongly on the momentum of the produced particle between 10 and 24 GeV/c. The effect of ..sigma../sup 0/ contamination on previous determinations of the polarization of inclusively produced ..lambda../sup 0/'s is discussed.

Inclusive production cross sections have been measured for the processes p-italic+A-italic..--> gamma../sup 0/+X (A-italic = Be, Cu, Pb) and for p-italic+Be..-->..Xi-bar/sup 0/+X. Data were taken at angles of 0, 2, 3.5, 7.3, and 9.8 mrad between the incident 400-GeV proton beam and the outgoing hyperon beam. Production cross sections for ..lambda.. and Lambda-bar production were measured at the same time. The A-italic dependence of the ..gamma../sup 0/ cross sections is discussed, along with interpretations in terms of various models.

The observation of substantial polarization of inclusively produced A hyperons at Fermilab established that spin is important at high energies. These studies continue and new results will be reported. The A polarization from hydrogen has been studied in detail to determine dependence on kinematic variables. Polarization from heavy targets has been measured for inclusively produced Ξ°, Ξ-, and Σ+ hyperons. A simple model of quark-antiquark pair production explains several features of the observed polarizations and will be discussed.

Received 7 February 1966DOI:https://doi.org/10.1103/PhysRevLett.16.536©1966 American Physical Society