New data on γ→p→→ηp with polarized photons and protons and their implications for N → Nη decays

Research output: Contribution to journalArticle


The polarization observables T,E,P,H, and G in photoproduction of η mesons off protons are measured for photon energies from threshold to W=2400 MeV (T), 2280 MeV (E), 1620 MeV (P,H), or 1820 MeV (G), covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, JüBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the Nη decay of nucleon resonances. A Nη-branching ratio of 0.33±0.04 for N(1650)1/2 is found, which reduces the large and controversially discussed Nη-branching ratio difference of the two lowest mass JP=1/2-resonances significantly.


  • CBELSA/TAPS Collaboration
External organisations
  • University of Bonn
  • Petersburg Nuclear Physics Institute (PNPI)
  • Helmholtz Institite for Radiation and Nuclear Physics
  • Ruhr-University Bochum
  • University Hospital Giessen and Marburg
  • University of Basel
  • Florida State University
Research areas and keywords


  • Baryon spectroscopy, Meson photoproduction, Polarization observables
Original languageEnglish
Article number135323
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Publication statusPublished - 2020 Apr 10
Publication categoryResearch
Externally publishedYes