Low-Mass (M<1.2 Gev/c^2) Sigma0 - Meson Produced in the System Pi+Pi- from the Reaction np --> np Pi+Pi- at Pn = 5.20 Gev/c^2

TL;DR

This study investigates low-mass Sigma0 mesons produced in np collisions at 5.20 GeV/c, identifying resonances with zero spin decaying into Pi+Pi-, and confirms their masses align with previous findings.

Contribution

It provides a detailed analysis of Sigma0 meson resonances with improved event selection and confirms their quantum numbers and mass sequence consistent with prior experiments.

Findings

Identified 8 peculiarities in Pi+Pi- mass distributions

All observed peculiarities have spin zero

Resonances match previously observed mass sequences

Abstract

The production and properties of the resonances in the system of Pi+Pi- were studied in the reaction np --> npPi+Pi- at the momentum of incident neutrons Pn=(5.20 +/- 0.12)GeV/c. In this work in comparison with previous ones we made more hard selection of events taking into account track measurement precise. In the distribution of the Pi+Pi- combinations effective masses we have found 8 peculiarities. All the observable peculiarities have spins equal to zero. There were no corresponding picks in the Pi-PI- and Pi-Pi0 - systems in the reactions np --> npPi+Pi- Pi- and np --> npPi-Pi0. So, we have observed a row of resonances with a set of quantum numbers 0+(0++) -- SIGMA0 - mesons decaying on the channel SIGMA0 --> Pi+Pi-. The obtained in other experiments masses coincide with the sequence of masses observed in our experiment. Especially good coincidence can be obtained in the K-matrix approach (see RPP).