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HK: Fachverband Physik der Hadronen und Kerne

HK 64: Hadronenstruktur und -spektroskopie X

HK 64.6: Vortrag

Freitag, 19. März 2010, 15:30–15:45, HG III

Charge symmetry breaking in pn → d π⁰ — •Arseniy Filin^2,3, Vadim Baru^1,2, Evgeny Epelbaum^1,3,4, Johann Haidenbauer^1,5, Christoph Hanhart^1,5, Alexander Kudryavtsev², and Ulf-G. Meißner^1,3,4,5 — 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.