Nature of $\bm{S}$-wave $\bm{NN}$ interaction and dibaryon production at nucleonic resonance thresholds

TL;DR

This paper models the $S$-wave nucleon-nucleon interaction considering dibaryon resonances near the $NN^*(1440)$ threshold, supported by recent experimental evidence, to deepen understanding of strong nuclear forces.

Contribution

It introduces a unified potential model incorporating isoscalar and isovector dibaryon resonances near the $NN^*(1440)$ threshold, supported by recent experimental data.

Findings

Evidence for near-threshold dibaryon resonances from WASA experiments.

Identification of two $S$-wave dibaryon resonances with specific isospin and parity.

Resonances provide new insights into the strong $NN$ interaction.

Abstract

Phase shifts and inelasticity parameters for $NN$ scattering in the partial-wave channels ${}^3S_1$--${}^3D_1$ and ${}^1S_0$ at energies $T_{\rm lab}$ from zero to about 1 GeV are described within a unified $NN$ potential model assuming the formation of isoscalar and isovector dibaryon resonances near the $NN^*(1440)$ threshold. Evidence for these near-threshold resonances is actually found in the recent WASA experiments on single- and double-pion production in $NN$ collisions. There, the excitation of the Roper resonance $N^*(1440)$ exhibits a structure in the energy dependence of the total cross section, which corresponds to the formation of dibaryon states with $I(J^\pi)=0(1^+)$ and $1(0^+)$ at the $NN^*(1440)$ threshold. These two $S$-wave dibaryon resonances may provide a new insight into the nature of the strong $NN$ interaction at low and intermediate energies.