Mainz 2012 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 2: Hadronenstruktur und -spektroskopie

HK 2.1: Group Report

Monday, March 19, 2012, 14:00–14:30, RW 2

Near-threshold pion production in diproton reactions with polarized beams and target at ANKE-COSY — •Sergey Dymov — Physikalisches Institut II, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany — Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia

An extensive experimental program for the near-threshold pion production in diproton reactions is undertaken at the ANKE-COSY spectrometer (Jülich). The program is aiming at isolating of the four-nucleon-pion contact interaction term appearing in the χ PT expansions of these processes. This will establish links between the pion production and other low energy phenomena within the χ PT approach.

The first step in the program was to measure the differential cross-section and the vector analysing power in the pp→ {pp}_sπ⁰ and pn→ {pp}_s π⁻ processes in the full angular range. These data allowed for partial wave analysis applying Watson’s theorem. To make the analysis more robust and independent of the uncertainties of the relative normalization, the spin correlation coefficients A_x,x and A_y,y in the pn→ {pp}_s π⁻ process were measured in the following experiment. The first results of the data analysis will be presented and the further development of the program discussed.

This work is supported by the COSY-FFE program.