Measurements of the total cross-section difference and the parameter CLL in pp scattering with longitudinally-polarized beam and target

We have measured the difference between the pp total cross-sections for parallel and anti-parallel longitudinal spin states at beam momenta of 3 and 6 GeV/ c. These results, combined with our previous measurements, at lower momenta, are useful in clarifying a striking structure appearing at around 1.5 GeV/ c. We have also measured for the first time, the spin-spin correlation parameter C_LL ( t) in pp elastic scattering at 6 GeV/ c. We observe evidence for an exchange with A ₁-like quantum-numbers.