The highest-energy measurement of $\Delta {\sigma }_L\mathrm{}\left(\mathrm{pp}\right)\mathrm{}$ and the first ever measurement of $\Delta {\sigma }_L\left(\mathrm{p¯}p\right)$, the differences between proton-proton and antiproton-proton total cross sections for pure longitudinal spin states, are described. Data were taken using 200-GeV/$c$ polarized beams incident on a polarized-proton target. The results are measured to be $\Delta {\sigma }_L\mathrm{}\left(\mathrm{pp}\right)=-42\pm 48\left(\mathrm{stat}\right)\pm 53\left(\mathrm{syst}\right)$ μb and $\Delta {\sigma }_L\left(\mathrm{p¯}p\right)=-256\pm 124\left(\mathrm{stat}\right)\pm 109\left(\mathrm{syst}\right)$ μb. Many tests of systematic effects were investigated and are described, and a comparison to theoretical predictions is also given. Measurements of parity nonconservation at $200$ GeV/$c$ in proton scattering and the first ever of antiproton scattering have also been derived from these data. The values are consistent with zero at the ${10}^{-5}$ level.

• Received 3 May 1996

DOI:https://doi.org/10.1103/PhysRevD.55.1159