Subthreshold ρ0 photoproduction on 3He

M. A. Kagarlis, Z. Papandreou, G. M. Huber, G. J. Lolos, A. Shinozaki, E. J. Brash, F. Farzanpay, M. Iurescu, A. Weinerman, G. Garino, K. Maruyama, O. Konno, K. Maeda, T. Terasawa, H. Yamazaki, T. Emura, H. Hirosawa, K. Niwa, H. Yamashita, S. EndoK. Miyamoto, Y. Sumi, A. Leone, R. Perrino, T. Maki, A. Sasaki, J. C. Kim

研究成果: Article査読

6 被引用数 (Scopus)


A large reduction of the ρ0 mass in the nuclear medium is reported, inferred from dipion photoproduction spectra in the 1 GeV region, for the reaction 3He(γ, π+π-)X with a 10% duty factor tagged-photon beam and the TAGX multiparticle spectrometer. The energy range spanned (800≤Eγ≤1120 MeV) lies mostly below the free-ρ0 production threshold, a region which is believed to be sensitive to modifications of light vector-meson properties at nuclear-matter densities. The values of the ρ0 mass extracted from the Monte Carlo fitting of the data were m*ρ0=642±40, 669±32, and 682±56 MeV/c2 for Eγ in the 800-880, 880-960, and 960-1040 MeV regions, respectively. These values were independently corroborated in a qualitative fashion by a measured, assumption-free, kinematical observable. This mass shift, far exceeding current mean-field-driven theoretical predictions, may be suggestive of a nucleonic source of modification or of a bound state in the nuclear mean field.

ジャーナルPhysical Review C - Nuclear Physics
出版ステータスPublished - 1999 8月

ASJC Scopus subject areas

  • 核物理学および高エネルギー物理学


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