Analysis of Nucleon Form Factor Data Reveals the e sup + e sup - ->Nucleon-Antinucleon Cross Section to Be Remarkably Larger Than the e sup + e sup - ->Proton-Antiproton One

摘要

A modified six-resonance VMD model for a description of the nucleon electromagnetic structure is constructed. It possesses correct analytic properties and the asymptotic behaviour in accordance with a quark model prediction for baryons. Only parameters with clear physical meaning are contained in the model. They are evaluated numerically in a simultaneous fit of all existing data on electric and magnetic nucleon form factors. As a result, the behaviour in the time-like region of electric and magnetic neutron form factors, for which there are no data up to now, has been predicted. In comparison with the corresponding behaviour of proton form factors above the nucleon-antinucleon threshold one finds them to exceed by a factor of five. Consequently the cross section of e sup + e sup - ->nucleon-antinucleon is expected to be roughly twenty-five-times as large as the cross section of e sup + e sup - ->proton-antiproton. 58 refs. (Atomindex citation 19:057357)