Münster 2002 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 12: Poster Session: Electromagentic and Hadronic Probes
HK 12.30: Poster
Dienstag, 12. März 2002, 10:30–12:45, Foyer Chemie
Search for Narrow Nucleon Resonances Below Pion Threshold — •M. Kohl, C. Rangacharyulu, A. Richter, and G. Schrieder — Institut f. Kernphysik, TU Darmstadt
The question if resonance states exist in the invariant mass region between the nucleon mass and the pion threshold is of particular importance for the structure of the nucleon. Since the decay energy of such states is not large enough to produce a pion, only electromagnetic or weak decay is possible, leading to extremely narrow decay widths. Recently, some experimental indications for such resonances have been reported. In pp scattering, narrow excited states of the nucleon at 1004, 1044, and 1094 MeV/c2 have been observed [1]. The high-resolution three-spectrometer facility of the A1 collaboration at the Mainz Microtron MAMI is particularly suited to verify the existence of such narrow nucleon resonances. A test experiment in the 1H(e,e’π+)X reaction provided first indication for a state at MX = 1007 MeV/c2 - yet with small significance. The status of the measurements will be reported.
[1] B. Tatischeff et al., Phys. Rev. Lett. 79 (1997) 601
Supported by DFG under contract RI 242/15-2.