Mainz 2012 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 38: Hadronenstruktur und -spektroskopie
HK 38.1: Gruppenbericht
Donnerstag, 22. März 2012, 16:30–17:00, RW 1
Threshold photoproduction of η and η ′ mesons off light nuclei - search for mesic nuclei — •Irakli Keshelashvili — University of Basel
The interaction of mesons with nuclei is a major source for our understanding of the strong interaction. In the case of short lived neutral mesons the only access is indirect, making use of final-state interaction. The mesons are produced with some initial reaction in the nucleus and then there interaction with the same nucleus is studied. It much discussed wether it is possible to form, via the strong interaction, quasi-bound states of mesons and nuclei, which would be the ideal tool for such studies. In particular, the case of η and η ′ mesons is of large interest and controversially discussed in the literature. Experimentally, signatures signatures for such states have been sought in the threshold behavior of meson production reactions, using different probes. We will present new results from the Crystal Ball/TAPS experiment at the Mainz MAMI accelerator for coherent photoproduction of η mesons from 3He and 7Li nuclei showing strong threshold enhancement in particular for the 3He case and discuss there relevance for the formation of an η-mesic state. Furthermore a fist attempt has been made to measure the threshold behavior of the photoproduction ot η ′ mesons from the deuteron and 3He. Preliminary results will be discussed.