Münster 2017 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 13: Structure and Dynamics of Nuclei II
HK 13.5: Vortrag
Dienstag, 28. März 2017, 12:15–12:30, F 2
Charge Symmetry Breaking in the dd → 4Heπ0 Reaction with WASA-at-COSY — •Maria Zurek — Forschungszentrum Jülich, Jülich, Germany
If protons and neutrons were treated equally by all types of interactions, isospin symmetry would be conserved. Since up and down quarks, which are the constituent quarks of the proton and the neutron, have different charges and masses, isospin symmetry is not an exact one. It is broken both by electromagnetic and strong interactions.
Investigations of the charge symmetry breaking dd → 4Heπ0 reaction is one of the primary goals for the WASA-at-COSY experiment. The aim is to provide experimental results for comparison with Chiral Perturbation Theory (χPT) predictions gaining information on the proton-neutron mass difference induced by the strong interaction.
First steps towards a theoretical understanding of the dd → 4Heπ0 reaction have found that the existing data are not sufficient for a precise determination of the parameters of χPT, and further data are required at sufficiently high energy where the p-wave contribution becomes important.
Results from a first measurement with the WASA detector setup at a beam momentum of 1.2 GeV/c had been already published, but the limited statistics did not allow a decisive interpretation. Thus, a second measurement using an improved detector setup aiming at higher statistics has been performed in spring 2014. The new results will be presented.