Charge Symmetry Breaking in dd->4He{\pi}0 with WASA-at-COSY

TL;DR

This study investigates charge symmetry breaking in the dd->4He{ extpi}0 reaction at higher energies to understand p-wave contributions, providing new experimental data with implications for nuclear quark mass effects.

Contribution

It extends previous measurements of charge symmetry breaking to higher energies, offering new differential cross section data and insights into p-wave contributions in pion production.

Findings

Total cross section measured as 118 pb with uncertainties.

Data consistent with s-wave pion production.

Provides first differential cross section data at this energy.

Abstract

Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd->4He{\pi}0 have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of p=1.2 GeV/c using the WASA-at-COSY facility. The total cross section amounts to sigma(tot) = (118 +- 18(stat) +- 13(sys) +- 8(ext)) pb and first data on the differential cross section are consistent with s-wave pion production.