Energy dependence of spin-spin effects inp−pelastic scattering at90°c.m.

The energy dependence of the spin-parallel and spin-antiparallel cross sections for $p_{\uparrow }+p_{\uparrow }\to p+p$ at ${90\mathrm{°}}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$ was measured for beam momenta between 6 and 12.75 GeV/c. The ratio ${\left(\frac{d\sigma }{\mathrm{dt}}\right)}_{\mathrm{parallel}}:{\left(\frac{d\sigma }{\mathrm{dt}}\right)}_{\mathrm{antiparallel}}$ at 90° is about 1.2 up to 8 GeV/c and then increases rapidly to a value of almost 4 near 11 GeV/c. Our data indicate that this ratio may depend only on the variable ${P_{\perp }}^2$, and suggests that the ratio may reach a limiting value of about 4 for large ${P_{\perp }}^2$.