Bonn 2010 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 64: Hadronenstruktur und -spektroskopie X
HK 64.6: Talk
Friday, March 19, 2010, 15:30–15:45, HG III
Charge symmetry breaking in pn → d π0 — •Arseniy Filin2,3, Vadim Baru1,2, Evgeny Epelbaum1,3,4, Johann Haidenbauer1,5, Christoph Hanhart1,5, Alexander Kudryavtsev2, and Ulf-G. Meißner1,3,4,5 — 1Institut für Kernphysik (Theorie) and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany — 2Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow, Russia — 3Helmholtz-Institut für Strahlen- und Kernphysik (Theorie), Universität Bonn, D-53115 Bonn, Germany — 4Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn, Germany — 5Institute for Advanced Simulation, Forschungszentrum Jülich, D-52425 Jülich, Germany
We study charge symmetry breaking (CSB) in the reaction pn → d π0. CSB manifests itself in a forward-backward asymmetry of the differential cross section measured recently at TRIUMF. A complete calculation of CSB effects at leading order in chiral perturbation theory is performed. A new leading-order operator is included. This allowed us to extract the strong contribution to the neutron-proton mass difference. The value obtained is consistent with the result of Gasser and Leutwyler based on Cottingham sum rule and an extraction from lattice QCD.