Moscow-type<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>NN</mml:mi></mml:math>potentials and three-nucleon bound states

Abstract

A detailed description of Moscow (M)-type potential models for the $\mathrm{NN}$ interaction is given. The microscopic foundation of these models, which appear as a consequence of the composite quark structure of nucleons, is discussed. M-type models are shown to arise naturally in a coupled channel approach when compound or bag-like six-quark states, strongly coupled to the $\mathrm{NN}$ channel, are eliminated from the complete multiquark wave function. The role of the deep-lying bound states that appear in these models is elucidated. By introducing additional conditions of orthogonality to these compound six-quark states, a continuous series of almost on-shell equivalent nonlocal interaction models, characterized by a strong reduction or full absence of a local repulsive core (M-type models), is generated. The predictions of these interaction models for $3N$ systems are analyzed in detail. It is shown that M-type models give, under certain conditions, a stronger binding of the $3N$ system than the original phase-equivalent model with nodeless wave functions. An analysis of the $3N$ system with the new versions of the Moscow $\mathrm{NN}$ potential describing also the higher even partial waves is presented. Large deviations from conventional $\mathrm{NN}$ force models are found for the momentum distribution in the high momentum region. In particular, the Coulomb displacement energy ${E}_{B}{(}^{3}\mathrm{He})\ensuremath{-}{E}_{B}{(}^{3}\mathrm{H})$---when ${E}_{B}{(}^{3}\mathrm{H})$ is extrapolated to the experimental value displays a promising agreement with experiment: $\ensuremath{\Delta}{E}_{C}\ensuremath{\simeq}$740 KeV. The validity and limits of two-body $\mathrm{NN}$ potentials in nuclei is discussed in the light of our analysis.