Dibaryon model for nuclear force and the properties of the 3N system
The dibaryon model for N N interaction, which implies the formation of an intermediate six-quark bag dressed by a σ field, is applied to the 3N system, where it results in a new three-body force of scalar nature between the six-quark bag and a third nucleon. A new multicomponent formalism is developed to describe three-body systems with nonstatic pairwise interactions and nonnucleonic degrees of freedom. Precise variational calculations of 3N bound states are carried out in the dressed-bag model including the new scalar three-body force. The unified coupling constants and form factors for 2N-and 3N-force operators are used in the present approach, in sharp contrast to conventional meson-exchange models. It is shown that this three-body force gives at least half the 3N total binding energy, while the weight of nonnucleonic components in the 3H and 3He wave functions can exceed 10%. The new force model provides a very good description of 3N bound states with a reasonable magnitude of the σN N coupling constant. A new Coulomb 3N force between the third nucleon and dibaryon is found to be very important for a correct description of the Coulomb energy and rms charge radius in 3He. In view of the new results for Coulomb displacement energy obtained here for A = 3 nuclei, an explanation for the long-term Nolen-Schiffer paradox in nuclear physics is suggested. The role of the charge-symmetry-breaking effects in the nuclear force is discussed.