The A1 Meson Exchange and OBEPs

The Al meson exchange is introduced into the Bonn OBEPs. This step improves consistency of calculations of the exchange currents effect.

Atlas of Polarization Observables

Muon capture in deuterium and the meson exchange current effect

Abstract One-meson exchange current effect in reaction μ − + d → 2 n + v μ is calculated by using the weak axial current operator which satisfies the nuclear continuity equation up to the order 1 M 2 ( M is the nucleon mass). In the vector part of the weak nuclear interaction the vector-isovector pion exchange currents are also included. Their contribution is found to be non-negligible. The nuclear wave functions are generated from the Paris, Reid soft-core and Bonn potential models. Our result is compatible with the previous one, obtained with only the static axial exchange currents included.

Explanation of Notation

For the presentation of all 288 polarization observables in the next section we have adopted the following scheme. Each observable is a function of the angle and the photon energy. With respect to the latter we have chosen five energies, namely 4.5 MeV, the maximum of the total cross section, 20 MeV, 60 MeV, 100 MeV, and 140 MeV. For each observable and for each of these energies we have studied the following topics: (i) The influence of meson exchange currents (MEC), isobar configurations (IC) and relativistic corrections (RC). Since the various potential models give qualitatively very similar results, we use in this case the r-space version of the Bonn model (OBEPR). (ii) The contribution…

Ingredients of Calculation

The calculation is done in the conventional framework of non-relativistic nuclear physics with nucleon, meson and isobar degrees of freedom but the dominant relativistic corrections of lowest order are included as outlined below.

Bonn potential and electron-deuteron scattering at high momentum transfer

Deuteron electrodisintegration d(e,e') near threshold is calculated using the various energy-independent Bonn potential versions. At high momentum transfer they lead to rather different results compared to other realistic NN potentials. This can only be partly explained by a different D-state admixture strength. The potential effect is particularly strong for the transverse form factor, but is also present for the longitudinal one. The latter is influenced in a similar way as the longitudinal part of the elastic deuteron form factor A(${\mathit{q}}^{2}$) which we have considered in addition.