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photoproduction off the proton at 
= 1.3-2.4 GeV村松 憲仁*; 土川 雄介; LEPS2/BGOegg Collaboration*; 他59名*
Physical Review C, 102(2), p.025201_1 - 025201_10, 2020/08
被引用回数：8 パーセンタイル：68.72(Physics, Nuclear)For the reaction 
, differential cross sections, photon beam asymmetries, and spin density matrix elements have been measured in the BGOegg experiment at the SPring-8 LEPS2 beamline by using a large acceptance electromagnetic calorimeter. A 1.3-2.4 GeV photon beam with high linear polarization has enabled a precision measurement of photon beam asymmetries 
and polarized spin density matrix elements 
over a wide angular range, especially above the total energy of about 2 GeV for the first time. The measured indicates the dominance of 
-channel resonances even at higher energies. The values at backward angles are not reproduced by the existing partial-wave analysis in the highest-energy region, providing new constraints to the contribution of nucleon resonances with high spins.
' bound nuclei in the 
C(
) reaction with simultaneous detection of decay products冨田 夏希*; 土川 雄介; LEPS2/BGOegg Collaboration*; 他61名*
Physical Review Letters, 124(20), p.202501_1 - 202501_7, 2020/05
被引用回数：10 パーセンタイル：61.46(Physics, Multidisciplinary)We measured missing mass spectrum of the C() reaction for the first time in coincidence with potential decay products from 
bound nuclei. We tagged an 
pair associated with the 
process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section was obtained to be 2.2~nb/sr at the 90% confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree production rate. Our results indicate a small branching fraction of the process and/or a shallow -nucleus potential.
