Relativistic Nucleon-Nucleon potentials using Dirac's constraint instant form dynamics

TL;DR

This paper develops energy-dependent relativistic nucleon-nucleon potentials using Dirac's constraint dynamics, fitting phase shifts up to 300 MeV and exploring high-energy behavior up to 3 GeV, revealing insights into short-range QCD effects and dibaryon formation.

Contribution

It introduces a novel relativistic potential model based on Dirac equations that accurately fits experimental phase shifts and explores high-energy nucleon interactions.

Findings

High-quality fits to phase shifts 0-300 MeV

Universal core potential from meson exchange dynamics

Evidence of dibaryon formation mechanisms

Abstract

The formalism of two coupled Dirac equations within constraint instant form dynamics is used to study the nucleon-nucleon interaction. The salient features and the final Schroedinger type equation is given. Explicitly energy dependent coupled channel potentials, for use in partial wave Schroedinger like equations, with nonlinear and complicated derivative terms, result. We developed the necessary numerics and study np and pp scattering phase shifts for energies 0-3 GeV and the deuteron bound state. The interactions are inspired by meson exchange of pi, eta, rho,omega and sigma mesons for which we adjust coupling constants. This yields, in the first instant, high quality fits to the Arndt phase shifts 0-300 MeV. Second, the potentials show a universal, independent from angular momentum, core potential which is generated from the relativistic meson exchange dynamics. Extrapolations towards higher energies, up to 3 GeV, allow to separate a QCD dominated short range zone as well as inelastic nucleon excitation mechanism contributing to meson production. A local and/or nonlocal optical model, in addition to the meson exchange Dirac potential, produces agreement between theoretical and data phase shifts. Third, the 1S0, 3P0 and 3P1 partial waves elicit a fusion/scission, for T-Lab<1GeV, and a fusion/fission, for T-Lab>1 GeV, mechanism for intermediate dibaryon formation.