Bochum 2009 – scientific programme

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HK: Fachverband Hadronen und Kerne

HK 67: Poster Session

HK 67.69: Poster

Thursday, March 19, 2009, 14:00–16:00, Audi-Max

Charge Symmetry Breaking in dd collisions with WASA-at-COSY* — •wojciech wglorz — Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany — Nuclear Physics Department of the University of Silesia, Katowice

Charge symmetry is a special case of isospin symmetry defined as an invariance under the rotation of 180^o around the second axis in isospin space. The isospin symmetry is broken on the QCD level due to the up and down quark mass difference and electromagnetic interactions. In contrast to isospin violation the Charge Symmetry Breaking (CSB) is not dominated by electro-magnetic interactions and, thus, well suited to study the QCD quark mass term.

Based on the recent high-precision measurements of CSB in np → d π⁰ at TRIUMF and dd → α π⁰ at IUCF significant progress in a common understanding of CSB within the framework of effective field theory has been achieved. Moreover, certain parameters have been identified necessary for a further theoretical analysis, like dd interactions in initial state state or p-wave contributions in dd → α π⁰. This has motivated a program on CSB in dd collisions at WASA-at-COSY. First experiments have been carried out since the end of 2007. A general outline of the program and the current status will be presented.

*Supported by FZ Jülich, BMBF, and Wallenberg Foundation