Alpha A1 Research Articles

Exact separation of natural and unnatural parity exchanges in nucleon-nucleon scattering

It is shown that certain combinations of s-channel helicity amplitudes correspond exactly to the exchange of definite sets of t-channel quantum numbers. Other formulae replace some commonly used ones true only in the infinite energy limit. The new method is applied to a study of 'A1' exchange in proton-proton scattering with interesting consequences. The A1 intercept emerges as alpha A1(O) approximately=-0.5. Certain earlier studies are shown to be unreliable in practice as well as in theory. It is shown, for example, that there is a substantial natural-parity component in the longitudinal total cross section difference Delta sigma L measured at Argonne. As a result of 'A1' not=0 at t=0, the absolute necessity for 'daughter' terms is demonstrated with some intriguing related conclusions.