Theory of single pion production in nucleon-nucleon scattering
Umland, Eric Alexander
Duck, Ian M.
Master of Arts
We have developed a phenomenological theory for the reaction NN+NNir based on the peripheral model and the formation and decay of dibaryon resonances. The peripheral graphs include one pion exchange with a monopole form factor at the TTNN vertex and the full TTN elastic scattering amplitude obtained from phase shift analyses and including off-shell corrections. Interfering with the one pion exchange graphs are one rho exchange graphs. Similiar monopole form factors are included at the pNN and pNA vertices. All form factors possess one adjustable parameter. We also study effects due to the still speculative J = 3~ and 2+ dibaryon resonances. The highly inelastic nature of these objects suggests that a single pion production reaction of the form NN+R+NA+NNTr presents the best opportunity for observing dibaryon manifestations. We calculated the fifth order spin dependent differential cross sections d+ (beam polarized up) and cr (beam polarized down) and the asymmetry (c+-c)/(a +). The peripheral model alone gives generally poor agreement with the kinematically-complete, beam polarized data of Hancock. Inclusion of the diproton amplitudes results in a general improvement in the fits, supporting the notion of such resonances in the 3 and 1D2 partial waves of the NN channel.