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村松 憲仁*; 土川 雄介; LEPS2 BGOegg Collaboration*; 他61名*
Physical Review C, 107(4), p.L042201_1 - L042201_5, 2023/04
被引用回数:0 パーセンタイル:0.02(Physics, Nuclear)For the first time, differential cross sections and photon beam asymmetries were measured for the reaction by using a linearly polarized photon beam up to 2.4 GeV and a liquid hydrogen target. The (980) photoproduction signal was clearly observed owing to the absence of contributions from vector-meson photoproduction. The results indicate the -channel exchange of vector mesons as a mechanism of the (980) photoproduction at approximate to 2.1 GeV, putting constraints on the nature of (980).
Bello Garrote, F. L.*; Sahin, E.*; 角田 佑介*; 大塚 孝治*; Grgen, A.*; Orlandi, R.; 他61名*
Physical Review C, 102(3), p.034314_1 - 034314_13, 2020/09
被引用回数:4 パーセンタイル:45.12(Physics, Nuclear)Detailed spectroscopy of neutron-rich odd- Cu isotopes is of great importance for studying the shell evolution in the region of Ni. Excited states in Cu were populated in the decay of Ni isotopes, which were produced by the in-flight fission at RIBF, RIKEN. The Ni isotopes were separated, identified, and implanted in a highly segmented Si detector array for the detection of the -decay electrons, while the delayed rays were detected by an array of HPGe cluster detectors. A level scheme of Cu was built up to 4 MeV, from which the location of the two previously known low-lying isomeric states was clarified. The level structure below 2 MeV was interpreted based on the results of the shell-model calculations and the systematics of odd- Cu isotopes, revealing the evolution of single-particle states in this region.
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:9 パーセンタイル:62.22(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.
Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他161名*
Physical Review Letters, 122(8), p.082001_1 - 082001_7, 2019/03
被引用回数:37 パーセンタイル:89.85(Physics, Multidisciplinary)We present the first measurements of absolute branching fractions of decays into , , and final states. The measurements are made using a data set comprising pairs collected at the resonance with the Belle detector at the KEKB collider. We first measure the absolute branching fraction for using a missing-mass technique, the result is . We subsequently measure the product branching fractions , , and with improved precision. Dividing these product branching fractions by the result for yields the following branching fractions: , , and . Our result for can be combined with branching fractions measured relative to to yield other absolute branching fractions.
Morales, A. I.*; Orlandi, R.; 他61名*
Physics Letters B, 781, p.706 - 712, 2018/06
被引用回数:21 パーセンタイル:85.39(Astronomy & Astrophysics)By studying the decay of the radioactive nuclei Co and Co produced at RIBF, RIKEN, the low-lying excited states in Ni were studied for the first time up to spin 8. These states originate from the valence neutrons occupying the orbit, and permit to investigate the seniority quantum number. The data reveal that the seniority isomerism of the 8 state disappears, and this phenomenon is explained by comparison with shell model calculations and the influence of spherical doubly-magic Ni.
Seidl, R.*; 谷田 聖; Belle Collaboration*; 他161名*
Physical Review D, 96(3), p.032005_1 - 032005_21, 2017/08
被引用回数:13 パーセンタイル:52.83(Astronomy & Astrophysics)The inclusive cross sections for dihadrons of charged pions and kaons () in electron-positron annihilation are reported. They are obtained as a function of the total fractional energy and invariant mass for any di-hadron combination in the same hemisphere as defined by the thrust event-shape variable and its axis. Since same-hemisphere dihadrons can be assumed to originate predominantly from the same initial parton, di-hadron fragmentation functions are probed. These di-hadron fragmentation functions are needed as an unpolarized baseline in order to quantitatively understand related spin-dependent measurements in other processes and to apply them to the extraction of quark transversity distribution functions in the nucleon. The di-hadron cross sections are obtained from a 655 fb data sample collected at or near the resonance with the Belle detector at the KEKB asymmetric-energy collider.
Adare, A.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他361名*
Physical Review C, 95(3), p.034904_1 - 034904_10, 2017/03
被引用回数:15 パーセンタイル:75.85(Physics, Nuclear)The PHENIX Collaboration has measured the ratio of the yields of to mesons produced in , Al, Au, and He+Au collisions at GeV over the forward and backward rapidity intervals . We find that the ratio in collisions is consistent with measurements at other collision energies. In collisions with nuclei, we find that in the forward (-going or He-going) direction, the relative yield of mesons to mesons is consistent with the value measured in collisions. However, in the backward (nucleus-going) direction, the meson is preferentially suppressed by a factor of . This suppression is attributed in some models to the breakup of the weakly bound meson through final-state interactions with comoving particles, which have a higher density in the nucleus-going direction. These breakup effects may compete with color screening in a deconfined quark-gluon plasma to produce sequential suppression of excited quarkonia states.
白鳥 昴太郎*; 今井 憲一; 佐甲 博之; 佐藤 進; 杉村 仁志; 市川 裕大; 谷田 聖; 他61名*
Physical Review Letters, 109(13), p.132002_1 - 132002_5, 2012/09
被引用回数:31 パーセンタイル:79.11(Physics, Multidisciplinary)J-PARCの中間子ビームを使って、1.92GeVの反応をこれまでにない1.4MeV(FWHM)という高分解能で測定しペンタクォークを探索した。報告されているの質量領域にはピーク構造は見つからなかった。得られたデータからペンタクォークの生成断面積の上限値として0.26b/srを得た。