Frankfurt 2014 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 53: Hadronenstruktur und -spektroskopie
HK 53.1: Gruppenbericht
Freitag, 21. März 2014, 11:00–11:30, HZ 3
Study of p→N→→ {pp}sπ reactions in the near-threshold region at ANKE-COSY — •Sergey Dymov for the ANKE collaboration — FZ-Juelich, Wilhelm-Johnen-Straße 52428 Jülich
For decription of pion reactions within the χPT framework it is important to establish that the same short-range NN → NNπ vertex contributes to both p-wave pion production, where both initial and final NN pairs are in S waves, and to other low energy phenomena.
The COSY-ANKE collaboration has embarked on an ambitious program of performing a complete set of measurements of the NN→{pp}s π reactions so that a full amplitude analysis can be carried out. By selecting events with excitation energy in the proton-proton system Epp < 3 MeV, the resulting diproton {pp}s is overwhelmingly in the 1S0 state. As parts of this program, measurements at Tp=353 MeV of the cross sections dσ/dΩ and proton analyzing powers Ayp in the p→p→ {pp}s π0 and the quasi-free p→n→ {pp}sπ− reactions were done at ANKE, as well as of the transverse spin correlations Ax,x and Ay,y in the n→ p→→ {pp}sπ− reaction.
The partial wave analysis results in three distinct solutions that can all describe reasonably well the measured values. However, the predictions for Ax,z are radically different. Hence even a low statistics measurement of this parameter would be sufficient to resolve the ambiguities. For a proton beam this can be achieved through the use of a Siberian snake. It is planned that such an experiment will be carried out at ANKE using the polarized deuterium target.