2026-03-23 京都大学
原子核標的中で陽子ビームによりφ中間子を生成。電子・陽電子対でφ中間子の生成を捉える。©️成木恵 Gemini 3 Flash Image
＜関連情報＞
- https://www.kyoto-u.ac.jp/ja/research-news/2026-03-23-1
- https://www.kyoto-u.ac.jp/sites/default/files/2026-03/web_2603_Naruki-c6731166c3529994ad8e1630ce89f37f.pdf
- https://academic.oup.com/ptep/advance-article/doi/10.1093/ptep/ptag042/8512258
J-PARC における30 GeV陽子・原子核反応による電子ペア崩壊を通じたφ中間子生成の初測定 First measurement of φ meson production in 30 GeV proton-nucleus reactions via di-electron decay at J-PARC
Satomi Nakasuga ,Yuhei Morino ,Kazuya Aoki ,Yoki Aramaki ,Daichi Arimizu ,Sakiko Ashikaga ,Wen-Chen Chang ,Ren Ejima ,Hideto En’yo ,Dairon Rodriguez Garces,…
Progress of Theoretical and Experimental Physics Published:09 March 2026
DOI:https://doi.org/10.1093/ptep/ptag042
Abstract
We present the first measurement of the production of the φ meson in 30 GeV proton-nucleus interactions on carbon and copper targets via the di-electron decay channel. The measurement was conducted at the high-momentum beamline of the J-PARC Hadron Experimental Facility, which was commissioned in 2020. The e+e− pairs were detected using the E16 spectrometer, during a commissioning run of the J-PARC E16 experiment. The φ mesons are successfully reconstructed on all experimental targets. The obtained yields are converted to the total production cross section, assuming a kinematical distribution of the event generator JAM. The total cross sections derived are 2.0 ± 0.9 (stat.) ± 1.0 (syst.) mb on the carbon target and 10.3 ± 4.4 (stat.) ± 4.4 (syst.) mb on the copper target. The mass-number dependence of the cross section is discussed using the parameter α, defined as σ∝Aα, resulting in α = 0.99 ± 0.38 (stat.) ± 0.34 (syst.). The extrapolation to A = 1, which means that the cross section of proton-proton reactions, is in good agreement with the existing measurements at comparable energies.
