Double pion production in $NN$ and $\bar{N}N$ collisions

TL;DR

This paper uses an effective Lagrangian approach to analyze double pion production in nucleon-nucleon and antinucleon-nucleon collisions, highlighting resonance contributions and matching experimental data up to 2.2 GeV.

Contribution

It provides a comprehensive analysis of resonance roles in double pion production, offering new insights into baryon resonances and guiding future experiments at various facilities.

Findings

Resonances like $ riangle$, $N^*(1440)$, $ riangle(1600)$, $ riangle(1620)$ significantly contribute.

Nucleon poles are important near the production threshold.

The model successfully describes experimental data up to 2.2 GeV.

Abstract

With an effective Lagrangian approach, we give a full analysis on the $NN \to NN\pi\pi$ and $\bar{N}N\to \bar{N}N\pi\pi$ reactions by exploring the roles of various resonances with mass up to 1.72 GeV. We find large contributions from $\Delta$, $N^*(1440)$, $\Delta(1600)$ and $\Delta(1620)$ resonances. Our calculations also indicate sizeable contributions from nucleon poles for the energies close to the threshold. A good description to the existing data of different isospin channels of $NN\to NN\pi\pi$ and $\bar{N}N\to \bar{N}N\pi\pi$ for beam energies up to 2.2 GeV is reached. Our results provide important implications to the ABC effect and guildlines to the future experimental projects at COSY, HADES and HIRFL-CSR. We point out that the \={P}ANDA at FAIR could be an essential place for studying the properties of baryon resonances and the data with baryon and anti-baryon in final states are worth analyzing.