Bochum 2009 – scientific programme

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HK: Fachverband Hadronen und Kerne

HK 61: Fundamental Symmetries

HK 61.8: Talk

Wednesday, March 18, 2009, 18:30–18:45, H-ZO 70

Feasibility studies for the measurement of η^′ → π⁺π⁻π⁰ decays in pp interactions — •Marcin J. Zielinski — Institut für Kernphysik and Jülich Center for Hadron Physics, 52425 Jülich, Germany — Institut of Physics, Jagiellonian University, 30-059 Cracow, Poland

One of the objectives of the physics programme with the recently commissioned WASA-at- COSY facility is the study of fundamental symmetries via the measurement of η and η^′ meson decays. Of particular interest are isospin-violating hadronic decays into 3π systems. These are driven by a term of the QCD Lagrangian that depends on the u−d quark mass difference. At COSY-Jülich the η and η^′ mesons can be produced with sizable cross sections in pp interactions. However, in such hadronic reactions the signal from the decays may be obscured by prompt meson production. In this presentation we will estimate the upper limit of the background from prompt pion production to the η^′ → 3π⁰ and η^′ → π⁺π⁻π⁰ decays. Using pp data from the COSY-11 experiment we have deduced differential cross sections for multi-meson production with an invariant mass in the vicinity of the η^′ meson. We obtain parameterisations of the total η^′ production cross section as well as of the prompt π⁺π⁻π⁰ production. We discuss in detail the feasibility of the planned WASA-at-COSY measurements on η^′ decays into π⁺π⁻π⁰.