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HK: Physik der Hadronen und Kerne

HK 5: Electromagnetic and Hadronic Probes I

HK 5.4: Vortrag

Montag, 11. März 2002, 17:30–17:45, D

First results of π⁰−η mixing angle measurement — •P. Hawranek¹, P. Hawranek¹, H. Machner², and H. Machner² — ¹Jagellonian University, Cracow, Poland — ²Institut für Kernphysik, Forschungszentrum Jülich, Jülich, Germany

Isospin symmetry may be broken - except for trivia reasons like Coulomb effects - via π⁰−η mixing. The mixing angle is related to the difference of the squared up and down quark masses. In order to measure this mixing angle we have studied the ratio of the two isospin related reactions pd→³Heπ⁰ and pd→³Hπ⁺ close to the η-threshold. A simple model Ref. 1 predicts the effect to be largest at large momentum transfer. The reactions have been measured at five different momenta in the vicinity of the η-threshold. Both recoils were measured simultaneously with an unusual magnetic spectrograph having two focal planes. The experiment will be presented as well as first data.

[1] A. Magiera and H. Machner, Nucl. Phys. A674 (2000) 515