High-precision, charge-dependent Bonn nucleon-nucleon potential

TLDR

The authors develop a charge‑dependent one‑boson‑exchange nucleon‑nucleon potential that fits world proton‑proton data below 350 MeV with χ² per datum of 1.01 and neutron‑proton data with χ² of 1.02. This is achieved by introducing two effective σ mesons with partial‑wave‑dependent parameters, using the Bonn full model for charge symmetry breaking, and representing the potential with covariant, nonlocal Feynman amplitudes for one‑boson exchange. The resulting CD‑Bonn potential reproduces NN data more accurately than any phase‑shift analysis or other potential, and its distinct off‑shell behavior yields larger binding energies in few‑ and many‑body systems, alleviating the persistent underbinding problem.

Abstract

We present a charge-dependent one-boson-exchange nucleon-nucleon $(\mathrm{NN})$ potential that fits the world proton-proton data below 350 MeV available in the year 2000 with a ${\ensuremath{\chi}}^{2}$ per datum of 1.01 for 2932 data and the corresponding neutron-proton data with ${\ensuremath{\chi}}^{2}/\mathrm{datum}$ $=1.02$ for 3058 data. This reproduction of the $\mathrm{NN}$ data is more accurate than by any phase-shift analysis and any other $\mathrm{NN}$ potential. This is achieved by the introduction of two effective $\ensuremath{\sigma}$ mesons the parameters of which are partial-wave dependent. The charge dependence of the present potential (which we call ``CD-Bonn'') is based upon the predictions by the Bonn full model for charge symmetry and charge-independence breaking in all partial waves with $J<~4.$ The potential is represented in terms of the covariant Feynman amplitudes for one-boson exchange which are nonlocal. Therefore, the off-shell behavior of the CD-Bonn potential differs in a characteristic way from commonly used local potentials and leads to larger binding energies in nuclear few- and many-body systems, where underbinding is a persistent problem.