The Role of the Isospin 3/2 Component in Elastic Neutron-Deuteron Scattering and in the Deuteron Breakup Reaction

We discuss the importance of the three-nucleon isospin [Formula: see text] component in elastic neutron-deuteron scattering and in the deuteron breakup reaction. The contribution of this amplitude originates from charge-independence breaking of the nucleon-nucleon potential. We study the magnitude of that contribution to the elastic scattering and breakup observables, taking the Av18 nucleon-nucleon potential alone or combined with the Urbana IX three-nucleon force as well as the locally regularized chiral N4LO nucleon-nucleon potential alone or supplemented by the chiral N2LO three-nucleon force. We find that the isospin [Formula: see text] component is important for the breakup reaction and the proper treatment of charge-independence breaking in this case requires the inclusion of the [Formula: see text] state with isospin [Formula: see text]. For neutron-deuteron elastic scattering the [Formula: see text] contributions are insignificant and charge-independence breaking can be accounted for by neglecting [Formula: see text] component and using the effective t-matrix generated with the so-called [Formula: see text] rule.

CHARGE INDEPENDENCE BREAKING IN MESON PRODUCTION?

We investigate by global and local fits whether existing data on pp → π+d and np → π0d have indications on charge dependent forces other than the Coulomb force and the effect of differing thresholds. We find evidence in the energy (or pion momentum) dependence of the total cross sections close to threshold.

Breaking of Charge Independence of Nucleon–Nucleon Interaction and Bulk Properties of Nuclear Matter

The effects of charge independence breaking of nucleon–nucleon interaction on the bulk properties of nuclear matter are investigated. Our results indicate that at high densities, the inclusion of charge dependence in the nucleon–nucleon potential affects the bulk properties of nuclear matter. However, at low densities, this effect is not considerable. It is seen that the change of our results for the nuclear matter calculations due to the breaking of the charge independence increases by increasing density. It is shown that the energy contribution of the 1S0 channel is sensitive to considering the charge dependence in the nucleon–nucleon interaction. It is indicated that the effects of charge independence breaking on the calculated equation of state of nuclear matter can be ignored.

QED–QCD INTERFERENCE EFFECT ON THE CHARGE-DEPENDENT N–N INTERACTION

The charge symmetry breaking and charge independence breaking N–N1 S 0 scattering length differences, Δa CSB and Δa CIB , are calculated by a resonating group method with a quark cluster model. By adding the QED–QCD interference effect to the quark mass difference and the electromagnetic interaction, the Δa CSB and Δa CIB values can be reproduced with model parameters constrained by the hadron isomultiplet mass splitting.