Large-angle proton-proton elastic scattering at 201 and 400 GeV/c

Proton-proton elastic scattering using 201- and 400-GeV/c extracted beams at Fermilab has been measured in the region 4.9<-t<14.4 GeV². Contrary to predictions of diffraction models, there is no sign of a second dip or "break," and the slope A in the fit exp(At) is smaller than predicted. It drops from 1.5 to 0.8 GeV^-2 over our t range. The shape of the t distribution can be fitted by the power law dσdt∝t^-8.4 which is close to a quantum-chromodynamics (QCD) prediction of t^-8. At fixed t the 201-GeV/c cross sections are about 2.3 times those at 400 GeV/c which is compatible with the QCD and constituent-interchange-model prediction that dσdt∝s^-10 at fixed t/s.