Production of eta and 3pi mesons in the pd->3HeX reaction at 1360 and 1450 MeV

TL;DR

This study measures cross sections for eta and 3pi meson production in proton-deuteron reactions at specific energies, revealing asymmetries and resonance effects that deepen understanding of meson production mechanisms.

Contribution

It provides new experimental data on meson production cross sections and analyzes isospin amplitudes and resonance roles at 1360 and 1450 MeV.

Findings

Strong forward-backward asymmetry in eta production

Analysis of isospin amplitude ratios in 3pi production

Hints of nucleon resonance involvement in 3pi systems

Abstract

The cross sections of the pd -> 3He eta, pd -> 3He pi0 pi0 pi0 and pd -> 3He pi+ pi- pi0 reactions have been measured at beam kinetic energies T_p= 1360 MeV and T_p= 1450 MeV using the CELSIUS/WASA detector setup. At both energies, the differential cross section dsigma/dOmega of the eta meson in the pd -> 3He eta reaction shows a strong forward-backward asymmetry in the CMS. The ratio between the pd -> 3He pi+ pi- pi0 and the pd -> 3He pi0 pi0 pi0 cross sections has been analysed in terms of isospin amplitudes. The reconstructed invariant mass distributions of the pi-pi, 3He-pi and 3He-2pi systems provide hints on the role of nucleon resonances in the 3pi production process.