B.J. VerWest

Determination of the πNN vertex function from np and pp charge exchange scattering

Abstract The π NN vertex function is studied using data for the reactions np → pn and p p → n n in the interval 0 t ⪅0.3(GeV/ c ) 2 at P L = 5, 8 and 25 GeV/ c . In this analysis the impact of the reggeized form for one-pion exchange with the residue function associated with the π NN vertex function is shown. For a monopole form for the vertex function the resulting mass parameter is Λ ≈ 890 MeV and for a Veneziano-type vertex function the asymptotic rate parameter is β ≈ 3. These results are consistent with information about the vertex function obtained from other reactions and theoretical studies.

Field theoretical calculation of NN pion production

Abstract A lowest-order Feynman diagram calculation of the process NN→NNπ at intermediate energies is presented. The calculation incorporates ρ-as well as π-meson exchange with hadronic form factors and N- and Δ 33 -resonance intermediate states and is in very good agreement with the recent differential cross-section spectra measurements near 800 MeV.

The measurement of KNN and KLL in at 800 MeV

Abstract The spin-transfer parameters K NN and K LL have been measured for at 0° and 800 MeV for neutron momenta between 700 and 1200 MeV c . Peak values of K NN and K LL are −0.30 ± 0.05 and −0.5 ± 0.1 respectively. These results are in substantial disagreement with VerWests field theoretic model.

Unique isospin-zero phase-shift solution for nucleon-nucleon scattering near 325 MeV

Abstract The recent measurement of D t in np scattering at 325 MeV by the BASQUE group permits a unique I = 0 phase shift solution to be determined, provided that the triplet G-wave phase shifts are constrained by theory.