Dielectron pairs from η meson decays at WASA detector
1 National Centre for Nuclear Research, Warsaw, Poland
2 Uppsala University, Uppsala, Sweden
* e-mail: Damian.Pszczel@ncbj.gov.pl
Published online: 1 February 2019
We present the results of the analysis of η → e+e−γ and η → e+e− decays. The experimental data were collected in proton-proton collisions at incident proton kinetic energy 1.4 GeV using the WASA detector and the COSY storage ring. We describe the extraction procedure of the η meson transition form factor, based on a sample of around 108 η mesons, and show an attempt to search for physics beyond the Standard Model that led to the setting of an upper limit on the coupling between photons and hypothetical dark bosons. We also provide an estimate of the branching ratio upper limit for the very rare η → e+e− decay.
© The Authors, published by EDP Sciences, 2019
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.