Bonn 2020 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 22: Hadron Structure and Spectroscopy V

HK 22.3: Talk

Wednesday, April 1, 2020, 14:45–15:00, J-HS A

Search for a narrow nucleon resonance at 1685 MeV — •Mariana Nanova, Volker Metag, and Kai-Thomas Brinkmann for the CBELSA/TAPS collaboration — II. Physikalisches Institut, Justus-Liebig-Universität Giessen

The excitation spectrum of the nucleon is still not sufficiently understood despite various long-lasting experimental and theoretical efforts. Recently the interest in the existence of pentaquark states has been renewed since such states have been observed in the charm sector. Particular attention has been paid to the recently claimed narrow structure observed at 1685 MeV in the Nπη channel [1], because this narrow structure could be identifed as the second member of the exotic anti-decuplet predicted in [2]. We have studied the two-meson photoproduction with the CB/TAPS detector system at the ELSA accelerator in Bonn in the reaction γp→ pπ⁰η. High statistics have been obtained by irradiating a liquid hydrogen target with photon beams in the incident energy range from 0.9 to 3.0 GeV. A kinematic fit has been used in the reconstruction and identification of the exit channels. In the search for the narrow structure at 1685 MeV acceptance corrected M(pη) invariant mass spectra will be presented and discussed.
[1] V. Kuznetsov et al., JETP Letters 106 (2017) 693
[2] D. Diakonov, V. Petrov and M. Polyakov, Z. Phys. A 359 (1997) 305.