Study of the Reaction $np \rightarrow np \pi^+ \pi^-$ at Intermediate Energies

TL;DR

This paper investigates the neutron-proton to neutron-proton pion-pion reaction at intermediate energies, demonstrating that different theoretical models are needed to describe the process below and above 3 GeV/c.

Contribution

It provides an analysis of the reaction mechanisms at various energies, showing the applicability of reggeized pion exchange above 3 GeV/c and the necessity of baryon exchange below 3 GeV/c.

Findings

Reggeized pion exchange describes the reaction above 3 GeV/c

Baryon exchange mechanism is needed below 3 GeV/c

Reaction characteristics vary with incident neutron momentum

Abstract

The reaction $np \rightarrow np \pi^+ \pi^-$ was studied at the various momenta of incident neutrons. It was shown that the characteristics of the reaction at the momenta above 3 GeV/c could be described by the model of reggeized $\pi$ exchange (OPER). At the momenta below 3 GeV/c, it was necessary to use additionally the mechanism of one baryon exchange (OBE).