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論文

Excited states in the neutron rich nuclei $$^{46}$$S and $$^{47}$$S

Begala, M.*; 宇都野 穣; 他85名*

Acta Physica Polonica B; Proceedings Supplement, 18(2), p.2-A17_1 - 2-A17_7, 2025/04

https://doi.org/10.5506/APhysPolBSupp.18.2-A17
 被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)

理化学研究所RIBFにて中性子過剰核$$^{46}$$Sと$$^{47}$$Sの励起状態を生成し、そこからの脱励起ガンマ線を観測した。$$^{46}$$Sについては新たに1500keV、2700keVのガンマ線を、$$^{47}$$Sについても1本のガンマ線を観測した。今後殻模型計算との比較から、どの状態が観測されたのかなどについて議論する予定である。

論文

Spectroscopy of deeply bound orbitals in neutron-rich Ca isotopes

Li, P. J.*; 宇都野 穣; 吉田 数貴; 他85名*

Physics Letters B, 855, p.138828_1 - 138828_11, 2024/08

https://doi.org/10.1016/j.physletb.2024.138828
 被引用回数：7 パーセンタイル：76.58(Astronomy & Astrophysics)

We report on the first measurement of unbound states in $$^{53}$$Ca and $$^{55}$$Ca, populated from $$^{54,56}$$Ca$$(p,pn)$$ reactions. Orbital angular momentum $$l$$ assignments were extracted from momentum distributions calculated with the distorted wave impulse approximation (DWIA). The resonances at 5516(41) keV in $$^{53}$$Ca and 6000(250) keV in $$^{55}$$Ca indicate a significant $$l$$ = 3 component, providing the first experimental evidence for the $$nu 0f_{7/2}$$ single-particle strength of unbound hole states in the neutron-rich Ca isotopes. The observed excitation energies and cross-sections point towards extremely localized and well separated strength distributions, with some fragmentation for the $$nu 0f_{7/2}$$ orbital in $$^{55}$$Ca. These results are in good agreement with predictions from shell-model calculations using the effective GXPF1Bs interaction and ab initio calculations and diverge markedly from the experimental distributions in the nickel isotones at Z = 28.

論文

Search for the decay $$B_s^0rightarrowetaeta$$

Bhuyan, B.*; 谷田 聖; Belle Collaboration*; 他185名*

Physical Review D, 105(1), p.012007_1 - 012007_7, 2022/01

https://doi.org/10.1103/PhysRevD.105.012007
 被引用回数：2 パーセンタイル：14.79(Astronomy & Astrophysics)

We report results from a search for the decay $$B_s^0rightarrowetaeta$$ using 121.4 fb$$^{-1}$$ of data collected at the $$Upsilon(5S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider. We do not observe any signal and set an upper limit on the branching fraction of $$14.3times 10^{-5}$$ at $$90%$$ confidence level. This result represents a significant improvement over the previous most stringent limit.

論文

Precise measurement of the $$D^0$$ and $$D^+$$ lifetimes at Belle II

Abudin$'e$n, F.*; 谷田 聖; Belle II Collaboration*; 他385名*

Physical Review Letters, 127(21), p.211801_1 - 211801_9, 2021/11

https://doi.org/10.1103/PhysRevLett.127.211801
 被引用回数：14 パーセンタイル：66.92(Physics, Multidisciplinary)

We report a measurement of the $$D^0$$ and $$D^+$$ lifetimes using $$D^0to K^-pi^+$$ and $$D^+to K^-pi^+pi^+$$ decays reconstructed in $$e^+e^-to cbar{c}$$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $$e^+e^-$$ collider. The data, collected at center-of-mass energies at or near the $$Upsilon(4S)$$ resonance, correspond to an integrated luminosity of $$72,{rm fb}^{-1}$$. The results, $$tau(D^0) = 410.5pm1.1,{rm(stat)}pm0.8,{rm(syst.)},{rm fs}$$ and $$tau(D^+) = 1030.4pm4.7,{rm(stat)}pm3.1,{rm(syst.)},{rm fs}$$, are the most precise to date and are consistent with previous determinations.

論文

Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment

江川 弘行; 足利 沙希子; 長谷川 勝一; 橋本 直; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 金原 慎二*; 七村 拓野; et al.

Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D02_1 - 021D02_11, 2019/02

https://doi.org/10.1093/ptep/pty149
 被引用回数：33 パーセンタイル：81.96(Physics, Multidisciplinary)

A double-$$Lambda$$ hypernucleus, $${}_{LambdaLambda}mathrm{Be}$$, was observed by the J-PARC E07 collaborationin nuclear emulsions tagged by the $$(K^{-},K^{+})$$ reaction. This event was interpreted as a production and decay of $$ {}_{LambdaLambda}^{;10}mathrm{Be}$$,$${}_{LambdaLambda}^{;11}mathrm{Be}$$, or $${}_{LambdaLambda}^{;12}mathrm{Be}^{*}$$ via $$Xi^{-}$$ capture in $${}^{16}mathrm{O}$$.By assuming the capture in the atomic 3D state, the binding energy of two $$Lambda$$ hyperons$$,$$($$B_{LambdaLambda}$$)of these double-$$Lambda$$ hypernuclei are obtained to be$$15.05 pm 0.11,mathrm{MeV}$$, $$19.07 pm 0.11,mathrm{MeV}$$, and $$13.68 pm 0.11,mathrm{MeV}$$, respectively. Based on the kinematic fitting, $${}_{LambdaLambda}^{;11}mathrm{Be}$$ is the most likely explanation for the observed event.

論文

Search for the rare decay of $$B^+ to ell^{,+} nu_{ell} gamma$$ with improved hadronic tagging

Gelb, M.*; 谷田 聖; Belle Collaboration*; 他185名*

Physical Review D, 98(11), p.112016_1 - 112016_13, 2018/12

AA2018-0766.pdf:0.99MB

https://doi.org/10.1103/PhysRevD.98.112016
 被引用回数：25 パーセンタイル：67.22(Astronomy & Astrophysics)

We present the result of the search for the rare $$B$$ meson decay of $$B^+ to ell^{,+} nu_{ell} gamma$$ with $$ell =e,mu$$. For the search the full data set recorded by the Belle experiment of $$711 , mathrm{fb}^{-1}$$ integrated luminosity near the $$Upsilon (4S)$$ resonance is used. Signal candidates are reconstructed for photon energies $$E_{gamma}$$ larger than $$1 , mathrm{GeV}$$ using a novel multivariate tagging algorithm. The novel algorithm fully reconstructs the second $$B$$ meson produced in the collision using hadronic modes and was specifically trained to recognize the signal signature in combination with hadronic tag-side $$B$$ meson decays. This approach greatly enhances the performance. Background processes that can mimic this signature, mainly charmless semileptonic decays and continuum processes, are suppressed using multivariate methods. The number of signal candidates is determined by analyzing the missing mass squared distribution as inferred from the signal side particles and the kinematic properties of the tag-side $$B$$ meson. No significant excess over the background-only hypothesis is observed and upper limits on the partial branching fraction $$ Delta mathcal{B} $$ with $$E_{gamma} > 1 , mathrm{GeV}$$ individually for electron and muon final states as well as for the average branching fraction of both lepton final states are reported. We find a Bayesian upper limit of $$Delta mathcal{B}( B^{+} to ell^{, +} nu_{ell} gamma) < 3.0 times 10^{-6}$$ at 90% CL and also report an upper limit on the first inverse moment of the light-cone distribution amplitude of the $$B$$ meson of $$lambda_B$$ at 90% CL.

論文

Study of $$K^0_S$$ pair production in single-tag two-photon collisions

増田 正孝*; 谷田 聖; Belle Collaboration*; 他185名*

Physical Review D, 97(5), p.052003_1 - 052003_20, 2018/03

AA2018-0514.pdf:1.09MB

https://doi.org/10.1103/PhysRevD.97.052003
 被引用回数：10 パーセンタイル：40.06(Astronomy & Astrophysics)

We report a measurement of the cross section for $$K^0_S$$ pair production in single-tag two-photon collisions, $$gamma^* gamma to K^0_S K^0_S$$, for $$Q^2$$ up to 30 GeV$$^2$$, where $$Q^2$$ is the negative of the invariant mass squared of the tagged photon. The measurement covers the kinematic range 1.0 GeV $$< W <$$ 2.6 GeV and $$|cos theta^*| < 1.0$$ for the total energy and kaon scattering angle, respectively, in the $$gamma^* gamma$$ center-of-mass system. These results are based on a data sample of 759 fb$$^{-1}$$ collected with the Belle detector at the KEKB asymmetric-energy $$e^+ e^-$$ collider. For the first time, the transition form factor of the $$f_2'(1525)$$ meson is measured separately for the helicity-0, -1, and -2 components and also compared with theoretical calculations. Finally, the partial decay widths of the $$chi_{c0}$$ and $$chi_{c2}$$ mesons are measured as a function of $$Q^2$$.

論文

Measurement of the higher-order anisotropic flow coefficients for identified hadrons in Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; 今井 憲一; 永宮 正治; 谷田 聖; PHENIX Collaboration*; 他385名*

Physical Review C, 93(5), p.051902_1 - 051902_8, 2016/05

AA2016-0390.pdf:0.48MB

https://doi.org/10.1103/PhysRevC.93.051902
 被引用回数：51 パーセンタイル：92.57(Physics, Nuclear)

Measurements of the anisotropic flow coefficients $$v_2{Psi_2 }$$, $$v_3{Psi_3 }$$, $$v_4{Psi_4 }$$, and $$v_4{Psi_2 }$$, for identified particles ($$pi^{pm}$$, $$K^{pm}$$, and $$p+bar{p}$$) at midrapidity, obtained relative to the event planes $$Psi_m$$ at forward rapidities in Au + Au collisions at $$sqrt{s_{NN}} =$$ 200 GeV, are presented as a function of collision centrality and particle transverse momenta $$p_T$$. The $$vn$$ coefficients show characteristic patterns consistent with hydrodynamical expansion of the matter produced in the collisions. For each harmonic $$n$$, a modified valence quark-number $$N_q$$ scaling [plotting $$v_n{Psi_m}/(N_q)^{n/2}$$ versus transverse kinetic energies $$(KE_{T})/N_q$$] is observed to yield a single curve for all the measured particle species for a broad range of $$KE_{T}$$. A simultaneous blast-wave model fit to the observed $$v_n{Psi_m}/(p_T)$$ coefficients and published particle spectra identifies radial flow anisotropies $$rho_n{Psi_m}$$ and spatial eccentricities $$s_n{Psi_m}$$ at freeze-out. These are generally smaller than the initial-state participant-plane geometric eccentricities $$epsilon_n{Psi_m^{PP}}$$ as also observed in the final eccentricity from quantum interferometry measurements with respect to the event plane.

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