EFFECT OF THE DELTA-(1236) ISOBAR ON THE 3-NUCLEON BOUND-STATES

Wave-function components containing a single Δ-isobar are included in the calculation of the three-nucleon bound states. The two-nucleon interaction acts in the 3S1-3D1 and 1S0 partial waves. Results are compared for two equivalent 1S0 potentials, one with and one without the coupling to the 5D0 nucleon-Δ channel. A technique for isolating the effect of the Δ is given. The presence of a Δ decreases the three-nucleon binding energy by 0.6 MeV, 0.5 MeV repulsion being a dispersive two-body effect, 0.1 MeV repulsion arising from the classic three-body force with an intermediate Δ. The disagreement of the present result with previous perturbation estimates for the contribution of the three-body force in the three-nucleon bound states is studied and found to be due to two reasons, the simplified one-pion-exchange nature of the force used in previous perturbation calculations and the neglect in the present calculation of higher two-body partial-waves. The effect of the Δ on the three-nucleon charge form factors is investigated. © 1979.