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論文

Large shape staggering in neutron-deficient Bi isotopes

Barzakh, A.*; Andreyev, A. N.; Raison, C.*; Cubiss, J. G.*; 他53名*

Physical Review Letters, 127(19), p.192501_1 - 192501_7, 2021/11

https://doi.org/10.1103/PhysRevLett.127.192501
 被引用回数：34 パーセンタイル：92.22(Physics, Multidisciplinary)

The changes in the mean-square charge radius (relative to $$^{209}$$Bi, magnetic moments and quadrupole moments of the neutron-deficient bismuth isotopes $$^{187,188,189,190}$$Bi were measured at ISOLDE (CERN). In the experiment, the in-source resonance-ionization spectroscopy technique was employed, which permits to study isotopes produced with rates as low as 0.1/sec. The radii of $$^{187.188.189}$$Bi manifest a large staggering, corresponding to a sudden increase of the radius of $$^{188}$$Bi relative to its $$^{187,189}$$Bi neighbors. This staggering effect occurs at neutron number $$N$$=105, where shape staggering was also observed in the mercury isotopes. Experimental results were compared with state-of-the-art mean-field calculations, which permit to identify the quasiparticle configurations compatible with the observed spin, parity and magnetic moment of the newly observed states.

論文

Search for $$B^0$$ decays to invisible final states ($$+gamma$$) at Belle

Ku, Y.*; 谷田 聖; Belle Collaboration*; 他153名*

Physical Review D, 102(1), p.012003_1 - 012003_9, 2020/07

https://doi.org/10.1103/PhysRevD.102.012003
 被引用回数：2 パーセンタイル：13.90(Astronomy & Astrophysics)

We report searches for $$B^0torm{invisible}$$ and $$B^0torm{invisible}+gamma$$ decays, where the energy of the photon is required to be larger than 0.5 GeV. These results are obtained from a $$711,{rm fb}^{-1}$$ data sample that contains $$772 times 10^6 Bbar{B}$$ pairs and was collected near the $$Upsilon,(4S)$$ resonance with the Belle detector at the KEKB $$e^+ e^-$$ collider. We observe no significant signal for either decay and set upper limits on their branching fractions at $$90%$$ confidence level of $$mathcal{B},(B^0torm{invisible}) < 7.8times10^{-5}$$ and $$mathcal{B},(B^0torm{invisible}+gamma) < 1.6times10^{-5}$$.

論文

$$J/psi$$ and $$psi(2S)$$ production at forward rapidity in $$p$$+$$p$$ collisions at $$sqrt{s}=510$$ GeV

Acharya, U. A.*; 長谷川 勝一; 今井 憲一*; 永宮 正治*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他353名*

Physical Review D, 101(5), p.052006_1 - 052006_13, 2020/03

https://doi.org/10.1103/PhysRevD.101.052006
 被引用回数：6 パーセンタイル：38.08(Astronomy & Astrophysics)

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section, mean transverse momentum, mean transverse momentum squared of inclusive $$J/psi$$ and cross-section ratio of $$psi(2S)$$ to $$J/psi$$ at forward rapidity in $$pp$$ collisions at $$sqrt{s} = 510$$ GeV via the dimuon decay channel. Comparison is made to inclusive $$J/psi$$ cross sections measured at $$sqrt{s} = 200$$ GeV and 2.76 - 13 TeV. The result is also compared to leading-order nonrelativistic QCD calculations coupled to a color-glass-condensate description of the low-$$x$$ gluons in the proton at low transverse momentum ($$p_T$$) and to next-to-leading order nonrelativistic QCD calculations for the rest of the $$p_T$$ range. These calculations overestimate the data at low $$p_T$$. While consistent with the data within uncertainties above $$approx 3$$ GeV/$$c$$, the calculations are systematically below the data. The total cross section times the branching ratio is BR $$dsigma^{J/psi}_{pp}/dy (1.2 < |y| < 2.2, 0 < p_T < 10$$ GeV/$$c$$) = 54.3 $$pm$$ 0.5 (stat) $$pm$$ 5.5 (syst) nb.

論文

Erratum; The Belle II physics book

Kou, E.*; 谷田 聖; Belle II Collaboration*; 他537名*

Progress of Theoretical and Experimental Physics (Internet), 2020(2), p.029201_1 - 029201_6, 2020/02

https://doi.org/10.1093/ptep/ptaa008
 被引用回数：135 パーセンタイル：99.68(Physics, Multidisciplinary)

In the original version of this manuscript, an error was introduced on pp.352. "2.7nb:1.6nb" has been corrected to "2.4nb:1.3nb" in the current online and printed version.

論文

The Belle II physics book

Kou, E.*; 谷田 聖; Belle II Collaboration*; 他537名*

Progress of Theoretical and Experimental Physics (Internet), 2019(12), p.123C01_1 - 123C01_654, 2019/12

https://doi.org/10.1093/ptep/ptz106
 被引用回数：460 パーセンタイル：99.96(Physics, Multidisciplinary)

We present the physics program of the Belle II experiment, located on the intensity frontier SuperKEKB $$e^+e^-$$ collider. Belle II collected its first collisions in 2018, and is expected to operate for the next decade. It is anticipated to collect 50/ab of collision data over its lifetime. This book is the outcome of a joint effort of Belle II collaborators and theorists through the Belle II theory interface platform (B2TiP), an effort that commenced in 2014. The aim of B2TiP was to elucidate the potential impacts of the Belle II program, which includes a wide scope of physics topics: B physics, charm, tau, quarkonium, electroweak precision measurements and dark sector searches. It is composed of nine working groups (WGs), which are coordinated by teams of theorist and experimentalists conveners: Semileptonic and leptonic B decays, Radiative and Electroweak penguins, $$phi_1$$ and $$phi_2$$ (time-dependent CP violation) measurements, $$phi_3$$ measurements, Charmless hadronic B decay, Charm, Quarkonium(-like), tau and low-multiplicity processes, new physics and global fit analyses. This book highlights "golden- and silver-channels", i.e. those that would have the highest potential impact in the field. Theorists scrutinised the role of those measurements and estimated the respective theoretical uncertainties, achievable now as well as prospects for the future. Experimentalists investigated the expected improvements with the large dataset expected from Belle II, taking into account improved performance from the upgraded detector.

論文

福島第一原子力発電所近隣における事故5年後の土壌調査

二宮 和彦*; 佐藤 志彦; 他53名*

KEK Proceedings 2017-6, p.31 - 34, 2017/11

https://lib-extopc.kek.jp/preprints/PDF/2017/1725/1725006.pdf

2011年3月に起こった、東京電力福島第一原子力発電所の事故により、福島県を中心とする陸域に大規模な放射能汚染が起こった。事故後の2011年6月には、日本地球惑星科学連合および日本放射化学会を中心とした有志の研究グループが、汚染状況の把握のための土壌採取のフィールド実験を実施した。これにより初期の汚染状況が明らかとなったが、航空機サーベイ等による汚染状況の把握は継続して行われているものの、実際に土壌を採取して汚染状況の詳細を把握する大規模な調査はそれ以降行われていない。そこで本研究では、福島県内の帰還困難区域を中心として土壌採取のフィールド実験を行い、その分析により現在の汚染状況の把握することを目的に実施した。福島県内の帰還困難区域を中心として、公共施設等を選定したうえで、各自治体との情報交換を行い、除染が行われていない地点を土壌採取場所として選択した。採取土壌は乾燥後、ゲルマニウム半導体検出器を用いた$$gamma$$線測定を実施し、土壌中の放射性セシウム濃度を定量した。なお本発表は本研究に関するシリーズ発表の第1弾で手法に言及した発表であり、詳細な成果は第2弾にて報告する。

論文

Search for $$XYZ$$ states in $$Upsilon(1S)$$ inclusive decays

Shen, C. P.*; 谷田 聖; Belle Collaboration*; 他153名*

Physical Review D, 93(11), p.112013_1 - 112013_11, 2016/06

AA2016-0391.pdf:1.04MB

https://doi.org/10.1103/PhysRevD.93.112013
 被引用回数：6 パーセンタイル：30.80(Astronomy & Astrophysics)

The branching fractions of the $$Upsilon(1S)$$ inclusive decays into final states with a $$J/psi$$ or a $$psi(2S)$$ are measured with improved precision to be $${cal B}(Upsilon(1S) to J/psi+ {rm anything})= (5.25 pm 0.13 ({rm stat}) pm 0.25({rm syst}))times10^{-4}$$ and $${cal B}(Upsilon(1S) to psi(2S)+ {rm anything})= (1.23 pm 0.17 ({rm stat}) pm 0.11({rm syst}))times10^{-4}$$. The first search for $$Upsilon(1S)$$ into $$XYZ$$ states that decay into a $$J/psi$$ or a $$psi(2S)$$ plus one or two charged tracks yields no significant signals for $$XYZ$$ states in any of the examined decay modes, and upper limits on their production rates in $$Upsilon(1S)$$ inclusive decays are determined.

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