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新山 雅之 所属 京都産業大学 理学部 物理科学科 職種 教授 |
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| 発行・発表の年月 | 2022/02 |
| 形態種別 | その他 |
| 標題 | Differential cross sections and photon beam asymmetries of $η$ photoproduction on the proton at $E_γ$ = 1.3-2.4 GeV |
| 執筆形態 | その他 |
| 著者・共著者 | T. Hashimoto,T. Nam,N. Muramatsu,J. K. Ahn,W. C. Chang,J. Y. Chen,M. L. Chu,S. Date,T. Gogami,H. Goto,H. Hamano,Q. H. He,K. Hicks,T. Hiraiwa,Y. Honda,T. Hotta,H. Ikuno,Y. Inoue,T. Ishikawa,I. Jaegle,J. M. Jo,Y. Kasamatsu,H. Katsuragawa,S. Kido,Y. Kon,S. Matsumoto,Y. Matsumura,M. Miyabe,K. Mizutani,T. Nakamura,T. Nakano,M. Niiyama,Y. Nozawa,Y. Ohashi,H. Ohnishi,T. Ohta,K. Ozawa,C. Rangacharyulu,S. Y. Ryu,Y. Sada,T. Shibukawa,H. Shimizu,R. Shirai,K. Shiraishi,E. A. Strokovsky,Y. Sugaya,M. Sumihama |
| 概要 | We have carried out exclusive measurements for the photoproduction of an
$\eta$ meson from a proton target with an egg-shaped calorimeter made of BGO crystals (BGOegg) and forward charged-particle detectors at the SPring-8 LEPS2 beamline. The differential cross sections and photon beam asymmetries of the $\gamma p \to \eta p$ reaction are measured in a center-of-mass energy ($W$) range of $1.82$-$2.32$ GeV and a polar angle range of $-1.0 < \cos{\theta^{\eta}_{\mathrm{c.m. } } } < 0.6$. The reaction is identified by selecting a proton and two $\gamma$'s produced by an $\eta$-meson decay. The kinematic fit method was employed to select the reaction candidate with the confidence level larger than $1$\%. A bump structure at $W$ = $2.0$-$2.3$ GeV in the differential cross section is confirmed at extremely backward $\eta$ polar angles, where the existing data are inconsistent with each other. This bump structure is likely associated with high-spin resonances that couple with $s\bar{s}$ quarks. The results of the photon beam asymmetries in a wide $\eta$ polar angle range are new for the photon beam energies exceeding $2.1$ GeV. These results are not reproduced by the existing partial wave analyses. They provide an additional constraint to nucleon resonance studies at high energies. |
| DOI | 10.1103/PhysRevC.106.035201 |
| PermalinkURL | http://arxiv.org/abs/2202.13688v1 |
| researchmap用URL | http://arxiv.org/pdf/2202.13688v1 |