High-energy pp and pp-bar forward elastic scattering and total cross sections

The present status of elastic pp and pp-bar scattering in the high-energy domain is reviewed, with emphasis on the forward and near-forward regions. The experimental techniques for measuring sigma/sub tot/, rho, and B are discussed, emphasizing the importance of the region in which the nuclear and Coulomb scattering interfere. The impact-parameter representation is exploited to give simple didactic demonstrations of important rigorous theorems based on analyticity, and to illuminate the significance of the slope parameter B and the curvature parameter C. Models of elastic scattering are discussed, and a criterion for the onset of ''asymptopia'' is given. A critique of dispersion relations is presented. Simple analytic functions are used to fit simultaneously the real and imaginary parts of forward scattering amplitudes for both pp and pp-bar, obtained from experimental data for sigma/sub tot/ and rho. It is found that a good fit can be obtained using only five parameters (with a cross section rising as ln2s), over the energy range 5 < √s < 62 GeV. The possibilities that (a) the cross section rises only as lns, (b) the cross section rises only locally as ln2s, and eventually goes to a constant value, and (c) the cross-section difference between pp and pp-bar does not vanish as s→infinity are examined critically. The nuclear slope parameters B are also fitted in a model-independent fashion. Examination of the fits reveals a new regularity of the pp-bar and the pp systems