Resonance-like structure near the ηd threshold in the γd→π0ηd reaction

T. Ishikawa, H. Fujimura, H. Fukasawa, R. Hashimoto, Q. He, Y. Honda, T. Iwata, S. Kaida, J. Kasagi, A. Kawano, S. Kuwasaki, K. Maeda, S. Masumoto, M. Miyabe, F. Miyahara, K. Mochizuki, N. Muramatsu, A. Nakamura, K. Nawa, Y. ObaraS. Ogushi, Y. Okada, K. Okamura, Y. Onodera, K. Ozawa, Y. Sakamoto, M. Sato, Hajime Shimizu, Hiroyuki Sugai, K. Suzuki, Y. Tajima, S. Takahashi, Y. Taniguchi, Y. Tsuchikawa, Hirohito Yamazaki, R. Yamazaki, H. Y. Yoshida

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6 Citations (Scopus)


To investigate the interaction between the nucleon N and nucleon resonance N(1535)1/2-, the ηd threshold structure connected to the isoscalar S-wave N-N(1535)1/2- system has been experimentally studied in the γd→π0ηd reaction at incident photon energies ranging from the reaction threshold to 1.15 GeV. A strong enhancement is observed near the ηd threshold over the three-body phase-space contribution in the ηd invariant-mass distribution. An analysis incorporating the known isovector resonance D12 with a spin parity of 2+ in the π0d channel reveals the existence of a narrow isoscalar resonance-like structure with 1- in the ηd system. Using a Flatté parametrization, the mass is found to be 2.427-0.006+0.013 GeV, close to the ηd threshold, and the width is (0.029-0.029+0.006GeV)+(0.00-0.00+0.41)pηc, where pη denotes the η momentum in the rest frame of the ηd system. The observed structure would be attributed to a predicted isoscalar 1-ηNN bound state from ηNN and πNN coupled-channel calculation, or an ηd virtual state owing to strong ηd attraction.

Original languageEnglish
Article numberL052201
JournalPhysical Review C
Issue number5
Publication statusPublished - 2021 Nov

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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