Polarized deuteron charge-exchange reaction $dp->{pp}_sN\pi$ in the Delta-isobar region

TL;DR

This study investigates the mechanisms of the polarized deuteron charge-exchange reaction in the Delta-isobar region, highlighting the dominance of the direct excitation mechanism and its partial success in explaining experimental data.

Contribution

It provides a detailed analysis of the reaction mechanisms at 1-2 GeV energies, emphasizing the role of the direct excitation of the Delta(1232) isobar and identifying limitations in describing certain polarization observables.

Findings

Direct mechanism dominates at the studied energies.

Model explains unpolarized cross sections and $T_{22}$ well.

Fails to describe the $T_{20}$ polarization observable.

Abstract

Mechanisms of the charge exchange reaction $dp\to \{pp\}_{\!s} N\pi$, where $\{pp\}_{\!s}$ is a two-proton system at low excitation energy, are studied at beam energies 1 -- 2 GeV and for invariant masses $M_X$ of the final $N\pi $ system that correspond to the formation of the $\Delta(1232)$ isobar. The direct mechanism, where the initial proton is excited into the $\Delta(1232)$, dominates and explains the existing data on the unpolarized differential cross section and spherical tensor analyzing power $T_{22}$ for $M_X> 1.2$ GeV/$c^2$. However, this model fails to describe $T_{20}.