Piersa, M.*; Korgul, A.*; Benito, J.*; Andreyev, A.; 他75名*
Physical Review C, 99(2), p.024304_1 - 024304_10, 2019/02
Excited states in Sn were investigated through the decay of In at the ISOLDE facility. The ISOLDE Resonance Ionization Laser Ion Source (RILIS) provided isomer-selective ionization for In, allowing us to study separately, and in detail, the -decay branch of In = (9/2) ground state and its = (1/2) isomer. Thanks to the large spin difference of the two -decaying states of In, it is possible to investigate separately the lower and higher spin states in the daughter, Sn, and thus to probe independently different single-particle and single-hole levels. We report here new transitions observed in the decay of In, including those assigned to the deexcitation of the neutron-unbound states.
橋本 直; 谷田 聖; 他67名*
Physics Letters B, 789, p.620 - 625, 2019/02
における不変質量分布において、つまりが2つの陽子に束縛する質量閾値以下に顕著なピークを観測した。 = 350650MeV/という比較的大きな運動量移行領域を選ぶことで、準弾性散乱()に続いて残りの2各紙に吸収される反応()をはっきり分離することができる。観測したピークの単純なフィットによってBreit-Wignerポール位置 MeV、幅 MeV、そして波ガウス形状因子パラメータMeV/という値が""というストレンジネスを含む新しい原子核束縛システムについて得られた。
Theint, A. M. M.*; 江川 弘行; 吉田 純也; 他7名*
Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D01_1 - 021D01_10, 2019/02
In the E373 experiment at KEK-PS, we have located nearly stopping events of hyperon candidates in nuclear emulsion. Among them, the identification of hyperon was performed with Constant Sagitta (CS) method by measuring multiple Coulomb scattering for 695 clearly stopping events. With use of Geant4 simulation, the parameters for the CS method were optimised and we obtained the number of real stopping events to be with 3.2% systematic error. The trapping probabilities of two hyperons for light and heavy nuclei were found to be % and %, respectively. For at least one trapping, the probabilities were % and % for light and heavy nuclei. These results are the first time to present the trapping probabilities of hyperons via hyperon capture at rest in the emulsion.
Berger, M.*; 谷田 聖; Belle Collaboration*; 他197名*
Physical Review D, 98(11), p.112006_1 - 112006_10, 2018/12
We report measurements of the branching fractions of the decays , and relative to the reference channel . The analysis is based on the full data sample collected at and close to resonance by the Belle detector at the KEKB asymmetric-energy collider corresponding to the integrated luminosity of 711 fb. We measure , and . The listed uncertainties are statistical and systematic, respectively.
Fulsom, B. G.*; 谷田 聖; Belle Collaboration*; 他197名*
Physical Review Letters, 121(23), p.232001_1 - 232001_8, 2018/12
We report the observation of decay based on analysis of the inclusive photon spectrum of fb of collisions at the center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy collider. We measure a branching fraction of , and derive an mass of MeV/, where the uncertainties are statistical and systematic, respectively. The significance of our measurement is greater than 7 standard deviations, constituting the first observation of this decay mode.
Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他175名*
European Physical Journal C, 78(11), p.928_1 - 928_8, 2018/11
We report evidence for the charged charmed-strange baryon with a signal significance of 3.9 with systematic errors included. The charged is found in its decay to in the substructure of decays. The measured mass and width are ~MeV/ and ~MeV, respectively, and the product branching fraction is . We also measure with greater precision than previous experiments, and present the results of a search for the charmonium-like state and its spin partner, , in the invariant mass spectrum. No clear signals of the or are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of pairs collected at the resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
熊田 高之; 他7名*
JPS Conference Proceedings (Internet), 22, p.011015_1 - 011015_5, 2018/11
Conventional deuterium contrast variation neutron reflectometry (NR) sometimes misleads when the deuterated SIMULATION samples fail to reproduce the structure of the REAL ones by delicate techniques such as spin-coating. On the other hand, the Spin contrast variation (SCV)-NR determines the structure from PH-dependent NR profiles of REAL samples. Therefore, the SCV-NR works not only as a technique which omits the cost of deuterium substitution, but also as a reliable technique to determine multi-layered surface and interface structure.
Aidala, C.*; 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397名*
Physical Review C, 98(5), p.054903_1 - 054903_11, 2018/11
Production of and mesons has been measured at midrapidity in CuAu collisions at =200 GeV. Measurements were performed in decay channel in the 1(2)-20 GeV/ transverse momentum range. A strong suppression is observed for and meson production at high transverse momentum in central CuAu collisions relative to the results scaled by the number of nucleon-nucleon collisions. In central collisions the suppression is similar to AuAu with comparable nuclear overlap. The ratio measured as a function of transverse momentum is consistent with -scaling parameterization down to 2 GeV/, its asymptotic value is constant and consistent with AuAu and and does not show any significant dependence on collision centrality. Similar results were obtained in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions as well as in collisions in a range of collision energies 3-1800 GeV. This suggests that the quark-gluon-plasma medium produced in CuCu collisions either does not affect the jet fragmentation into light mesons or it affects the and the same way.
Cubiss, J. G.*; Barzakh, A. E.*; Andreyev, A.; 他57名*
Physics Letters B, 786, p.355 - 363, 2018/11
The first accurate measurements of the -decay branching ratio and half-life of the I=1/2 ground state in Tl have been made, along with the first determination of the magnetic moments and I=1/2 spin assignments of the ground states in Au. The results are discussed within the complementary systematics of the reduced -decay widths and nuclear g factors of low-lying, I=1/2states in the neutron-deficient lead region. The findings shed light on the unexpected hindrance of the 1/2 1/2, Tl Au decay, which is explained by a mixing of 3sand 2d configurations in Au, whilst Tl remains a near-pure 3s. This conclusion is inferred from the g factor of Au which has an intermediate value between those of 3s and 2d states. A similar mixed configuration is proposed for the I=1/2 ground state of Au. This mixing may provide evidence for triaxial shapes in the ground states in these nuclei.
Xu, Q. N.*; 谷田 聖; Belle Collaboration*; 他176名*
Physical Review D, 98(7), p.072001_1 - 072001_17, 2018/10
We report the measurement of , with decays to and using 941 fb of data collected with the Belle detector at the KEKB asymmetric-energy collider. The mass and width are measured to be MeV/ and MeV, respectively. First observation of with a significance of including systematic error is obtained, and the mass is measured to be MeV/. The products of the two-photon decay width and branching fraction of decays to are determined to be eV for and eV for . A new decay mode for the to with is observed with a statistical significance of . The mass and width are determined to be MeV/ and MeV. The cross sections for and are measured for the first time.
Aidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他287名*
Physical Review D, 98(7), p.072004_1 - 072004_13, 2018/10
Dihadron and isolated direct photon-hadron angular correlations are measured in collisions at GeV. The correlations are sensitive to nonperturbative initial-state and final-state transverse momentum and in the azimuthal nearly back-to-back region . In this region, transverse-momentum-dependent evolution can be studied when several different hard scales are measured. To have sensitivity to small transverse momentum scales, nonperturbative momentum widths of , the out-of-plane transverse momentum component perpendicular to the trigger particle, are measured. These widths are used to investigate possible effects from transverse-momentum-dependent factorization breaking. When accounting for the longitudinal momentum fraction of the away-side hadron with respect to the near-side trigger particle, the widths are found to increase with the hard scale; this is qualitatively similar to the observed behavior in Drell-Yan and semi-inclusive deep-inelastic scattering interactions. The momentum widths are also studied as a function of center-of-mass energy by comparing to previous measurements at GeV. The nonperturbative jet widths also appear to increase with at a similar , which is qualitatively consistent to similar measurements in Drell-Yan interactions.
Wang, B.*; He, H.*; Naeem, M.*; Lan, S.*; Harjo, S.; 川崎 卓郎; Nie, Y.*; Wang, X.-L.*; 他7名*
Scripta Materialia, 155, p.54 - 57, 2018/10
The deformation behavior of an equi-atomic face-centered-cubic CoCrFeNi high entropy alloy was investigated by in-situ neutron diffraction under tensile loading up to 40% applied strain. A three-stage deformation behavior was fully captured by lattice strain and texture evolution. In spite of the chemical complexity, the deformation in CoCrFeNi is dominated by dislocation activities. Analysis of diffraction and microscopy data shows that the deformation progresses from dislocation slip to severe entanglement, where a sharp increase in dislocation density was observed. The neutron diffraction data, corroborated by transmission electron microscopy analysis, provided microscopic insights of the previously reported three-stage hardening behavior.
Tamponi, U.*; 谷田 聖; Belle Collaboration*; 他174名*
European Physical Journal C, 78(8), p.633_1 - 633_10, 2018/08
We study bottomonium production in association with an meson in annihilations near the , at a center of mass energy of GeV. The results are based on the fb data sample collected by the Belle experiment at the asymmetric energy KEKB collider. Only the meson is reconstructed and the missing-mass spectrum of candidates is investigated. We observe the process and find evidence for the process, while no significant signals of , , nor are found. Cross sections for the studied processes are reported.
Sibidanov, A.*; 谷田 聖; Belle Collaboration*; 他187名*
Physical Review Letters, 121(3), p.031801_1 - 031801_8, 2018/07
We report the result of a search for the decay . The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic -meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of or a frequentist 90% confidence level interval on the branching fraction of . This result is obtained from a 711 fb data sample that contains pairs, collected 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347名*
Physical Review C, 97, p.064904_1 - 064904_11, 2018/06
We present measurements of the transverse-momentum dependence of elliptic flow for identified pions and (anti)protons at midrapidity (), in 0% - 5% central + Au and He + Au collisions at = 200 GeV. When taken together with previously published measurements in + Au collisions at = 200 GeV, the results cover a broad range of small-collision-system multiplicities and intrinsic initial geometries. We observe a clear mass-dependent splitting of in + Au and He + Au collisions, just as in large nucleus-nucleus ( + ) collisions, and a smaller splitting in + Au collisions. Both hydrodynamic and transport model calculations successfully describe the data at low ( GeV/), but fail to describe various features at higher . In all systems, the values follow an approximate quark-number scaling as a function of the hadron transverse kinetic energy per constituent quark(), which was also seen previously in + collisions.
新山 雅之*; 谷田 聖; Belle Collaboration*; 他167名*
Physical Review D, 97(7), p.072005_1 - 072005_21, 2018/04
We measure the inclusive production cross sections of hyperons and charmed baryons from annihilation using a 800 fb data sample taken near the resonance with the Belle detector at the KEKB asymmetric-energy collider. The feed-down contributions from heavy particles are subtracted using our data, and the direct production cross sections are presented for the first time. The production cross sections divided by the number of spin states for hyperons follow an exponential function with a single slope parameter except for the resonance. Suppression for and hyperons is observed. Among the production cross sections of charmed baryons, a factor of three difference for states over states is observed. This observation suggests a diquark structure for these baryons.
Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他178名*
European Physical Journal C, 78(3), p.252_1 - 252_8, 2018/03
We report the first observation of the charmed-strange baryon with a significance greater than 5. The is found in its decay to in decays. The measured mass and width are MeV/ and MeV, respectively, and the product branching fraction is =. We also measure with improved precision, and search for the charmonium-like state and its spin partner, , in the invariant mass spectrum. No clear signals of the nor its spin partner are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of pairs collected at the resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
Yelton, J.*; 谷田 聖; Belle Collaboration*; 他177名*
Physical Review D, 97(5), p.051102_1 - 051102_6, 2018/03
Using the entire Belle data sample of 980 of collisions, we present the results of a study of excited charmed baryons in the decay mode . We show confirmation of four of the five narrow states reported by the LHCb Collaboration: the , , , and .
Yang, S. B.*; 江川 弘行; 長谷川 勝一; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; et al.
Physical Review Letters, 120, p.132505_1 - 132505_5, 2018/03
We report on the first observation of rays emitted from an -shell hypernucleus, F. The energy spacing between the ground state doublet, and states, of F is determined to be keV by measuring the -ray energy of the transition. In addition, three -ray peaks are observed and assigned as , , and transitions. The excitation energies of the and states are determined to be keV and keV, respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing - and -shell hypernuclear data.
Yelton, J.*; 谷田 聖; Belle Collaboration*; 他187名*
Physical Review D, 97(3), p.032001_1 - 032001_8, 2018/02
Using a data sample of 980 of annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy collider, we report the results of a study of the decays of the charmed baryon into hadronic final states. We report the most precise measurements to date of the relative branching fractions of the into , , , and , as well as the first measurements of the branching fractions of the into , , and , all with respect to the decay. In addition, we investigate the resonant substructure of these modes. Finally, we present a limit on the branching fraction for the decay .