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論文

Development of compact high field pulsed magnet system for new sample environment equipment at MLF in J-PARC

渡辺 真朗; 野尻 浩之*; 伊藤 晋一*; 河村 聖子; 木原 工*; 益田 隆嗣*; 佐原 拓郎*; 左右田 稔*; 高橋 竜太

JPS Conference Proceedings (Internet), 25, p.011024_1 - 011024_5, 2019/03

https://doi.org/10.7566/JPSCP.25.011024

近年、中性子や放射光をプローブとした数10T以上の強磁場下で行う実験・研究への要望が増えてきている。強磁場装置を用いた中性子散乱実験は、例えば、磁場誘起超伝導体などにおける強磁場中磁気相関の研究やマルチフェロイック物質などの新しい凝縮系の研究などが挙げられる。J-PARC MLFでは、強磁場パルスマグネットシステムの開発をおこなった。一般的に数10テスラ以上の強磁場装置は大規模になるが、開発する装置はMLFの既存のビームラインに対して設置可能な小型な装置でなければならない。そこで数ミリ秒程度磁場を発生させるパルスマグネットシステムを開発した。パルス磁場にすることで、強磁場を達成しつつエネルギー・パワーを抑えることで装置の小型化が可能である。30テスラを発生可能なパルスマグネットシステムを実現するためには、高電圧・大電流パルス電源および、強磁場に耐えられるコイルと試料スティックが必要である。本発表では、開発したパルスマグネットシステムの詳細およびMLFビームライン(HRC)にて行なった中性子ビーム利用実験でのパルスマグネットシステムの状況について報告する。

論文

Hadronic Paschen-Back effect

岩崎 幸生; 岡 眞; 鈴木 渓*; 吉田 哲也*

Physics Letters B, 790, p.71 - 76, 2019/03

https://doi.org/10.1016/j.physletb.2018.10.024
 被引用回数：1 パーセンタイル：14.11(Astronomy & Astrophysics)

ヘビークォークを含むメソンに強い磁場がかかったときにスペクトルおよび波動関数がどのように変化するかを磁場の強さの関数として解析した。

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

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

Trapping probability of strangeness via $$mathrm{Xi}^{-}$$ hyperon capture at rest in nuclear emulsion

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

https://doi.org/10.1093/ptep/pty147

In the E373 experiment at KEK-PS, we have located nearly $$2 times 10^{4}$$ stopping events of $$Xi^{-}$$ hyperon candidates in nuclear emulsion. Among them, the identification of $$Xi^{-}$$ 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 $$Xi^{-}$$ stopping events to be $$432.3 pm 7.6^{+0.0}_{-14.0}$$ with 3.2% systematic error. The trapping probabilities of two $$Lambda$$ hyperons for light and heavy nuclei were found to be $$5.0 pm 1.7$$% and $$4.2 pm 1.4$$%, respectively. For at least one $$Lambda$$ trapping, the probabilities were $$69.4 pm 8.1$$% and $$51.1 pm 5.7$$% for light and heavy nuclei. These results are the first time to present the trapping probabilities of $$Lambda$$ hyperons via $$Xi^{-}$$ hyperon capture at rest in the emulsion.

論文

Measurement of the branching fraction and time-dependent $$CP$$ asymmetry for $$B^0to J/psipi^0$$ decays

Pal, B.*; 谷田 聖; Belle Collaboration*; 他158名*

Physical Review D, 98(11), p.112008_1 - 112008_8, 2018/12

https://doi.org/10.1103/PhysRevD.98.112008
 パーセンタイル：100(Astronomy & Astrophysics)

We measure the branching fraction and time-dependent $$CP$$-violating asymmetry for $$B^0to J/psipi^0$$ decays using a data sample of 711 $${rm fb^{-1}}$$ collected on the $$Upsilon(4S)$$ resonance by the Belle experiment running at the KEKB $$e^+e^-$$ collider. The branching fraction is measured to be $$mathcal{B}(B^0to J/psipi^0) = [1.62,pm 0.11~({rm stat}) pm0.07~({rm syst})]times 10^{-5}$$, which is the most precise measurement to date. The measured $$CP$$ asymmetry parameters are $$mathcal{S} = -0.59,pm 0.19~({rm stat}) pm 0.03~({rm syst})$$ and $$mathcal{A} = -0.15,pm 0.14~({rm stat}),^{+0.04}_{-0.03}~({rm syst})$$. The mixing-induced $$CP$$ asymmetry ($$mathcal{S}$$) differs from the case of no $$CP$$ violation by 3.0 standard deviations, and the direct $$CP$$ asymmetry ($$mathcal{A}$$) is consistent with zero.

論文

Measurement of the decays $$Lambda_cto Sigmapipi$$ at Belle

Berger, M.*; 谷田 聖; Belle Collaboration*; 他197名*

Physical Review D, 98(11), p.112006_1 - 112006_10, 2018/12

https://doi.org/10.1103/PhysRevD.98.112006
 被引用回数：2 パーセンタイル：64.74(Astronomy & Astrophysics)

We report measurements of the branching fractions of the decays $$Lambda^+_ctoSigma^+pi^-pi^+$$, $$Lambda^+_ctoSigma^0pi^+pi^0$$ and $$Lambda^+_ctoSigma^+pi^0pi^0$$ relative to the reference channel $$Lambda^+_cto pK^-pi^+$$. The analysis is based on the full data sample collected at and close to $$Upsilon(4S)$$ resonance by the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider corresponding to the integrated luminosity of 711 fb$$^{-1}$$. We measure $${cal B}(Lambda^+_crightarrowSigma^+pi^-pi^+)/{cal B}(Lambda^+_cto pK^-pi^+) = 0.706~pm 0.003~pm 0.029$$, $${cal B}(Lambda^+_crightarrowSigma^0pi^+pi^0)/{cal B}(Lambda^+_cto pK^-pi^+) = 0.491~pm 0.005~pm 0.028$$ and $${cal B}(Lambda^+_crightarrowSigma^+pi^0pi^0)/{cal B}(Lambda^+_cto pK^-pi^+) = 0.198~pm 0.006~pm 0.016$$. The listed uncertainties are statistical and systematic, respectively.

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

https://doi.org/10.1103/PhysRevD.98.112016
 パーセンタイル：100(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

First evidence for cos 2$$beta >$$ 0 and resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle ambiguity

足立 一郎*; 谷田 聖; Belle Collaboration*; 他421名*

Physical Review Letters, 121(26), p.261801_1 - 261801_11, 2018/12

https://doi.org/10.1103/PhysRevLett.121.261801
 被引用回数：1 パーセンタイル：49.95(Physics, Multidisciplinary)

We present first evidence that the cosine of the $$CP$$-violating weak phase $$2beta$$ is positive, and hence exclude trigonometric multifold solutions of the CKM Unitarity Triangle using a time-dependent Dalitz plot analysis of $$B^{0} to D^{(*)} h^{0}$$ with $$D to K_{S}^{0} pi^{+} pi^{-}$$ decays, where $$h^{0} in {pi^{0}, eta, omega }$$ denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BaBar and Belle experiments collected at the $$Upsilon(4S)$$ resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain $$( 471 pm 3 )times 10^6, Bbar{B}$$ pairs recorded by the BaBar detector and $$( 772 pm 11 )times 10^6, Bbar{B}$$ pairs recorded by the Belle detector. The results of the measurement are $$sin{2beta} = 0.80 pm 0.14 ,(rm{stat.}) pm 0.06 ,(rm{syst.}) pm 0.03 ,(rm{model})$$ and $$cos{2beta} = 0.91 pm 0.22 ,(rm{stat.}) pm 0.09 ,(rm{syst.}) pm 0.07 ,(rm{model})$$. The result for the direct measurement of the angle $$beta$$ of the CKM Unitarity Triangle is $$beta = left( 22.5 pm 4.4 ,(rm{stat.}) pm 1.2 ,(rm{syst.}) pm 0.6 ,(rm{model}) right)^{circ}$$. The quoted model uncertainties are due to the composition of the $$D^{0} to K_{S}^{0} pi^{+} pi^{-}$$ decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics $$e^{+}e^{-} to cbar{c}$$ data sample. CP violation is observed in $$B^{0} to D^{(*)} h^{0}$$ decays at the level of $$5.1$$ standard deviations. The significance for $$cos{2beta} > 0$$ is $$3.7$$ standard deviations. The trigonometric multifold solution $$pi/2 - beta = (68.1 pm 0.7)^{circ}$$ is excluded at the level of $$7.3$$ standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.

論文

Observation of $$Upsilon(2S)togamma eta_{b}(1S)$$ decay

Fulsom, B. G.*; 谷田 聖; Belle Collaboration*; 他197名*

Physical Review Letters, 121(23), p.232001_1 - 232001_8, 2018/12

https://doi.org/10.1103/PhysRevLett.121.232001
 パーセンタイル：100(Physics, Multidisciplinary)

We report the observation of $$Upsilon(2S)togammaeta_{b}(1S)$$ decay based on analysis of the inclusive photon spectrum of $$24.7$$ fb$$^{-1}$$ of $$e^+ e^-$$ collisions at the $$Upsilon(2S)$$ center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy $$e^+ e^-$$ collider. We measure a branching fraction of $$mathcal{B}(Upsilon(2S)togammaeta_{b}(1S))=(6.1^{+0.6+0.9}_{-0.7-0.5})times 10^{-4}$$, and derive an $$eta_{b}(1S)$$ mass of $$9394.8^{+2.7+4.5}_{-3.1-2.7}$$ MeV/$$c^{2}$$, 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.

論文

Evidence of a structure in $$bar{K}^{0} Lambda _{c}^{+}$$ consistent with a charged $$Xi _c(2930)^{+}$$, and updated measurement of $$bar{B}^{0} rightarrow bar{K}^{0} Lambda _{c}^{+} bar{Lambda }_{c}^{-}$$ at Belle

Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他175名*

European Physical Journal C, 78(11), p.928_1 - 928_8, 2018/11

https://doi.org/10.1140/epjc/s10052-018-6425-5

We report evidence for the charged charmed-strange baryon $$Xi_{c}(2930)^+$$ with a signal significance of 3.9$$sigma$$ with systematic errors included. The charged $$Xi_{c}(2930)^+$$ is found in its decay to $$K_{S}^{0} Lambda_{c}^+$$ in the substructure of $$bar{B}^{0} to K^{0}_{S} Lambda_{c}^{+} bar{Lambda}_{c}^{-}$$ decays. The measured mass and width are $$[2942.3 pm 4.4 (rm stat.) pm 1.5(rm syst.)]$$~MeV/$$c^{2}$$ and $$[14.8 pm 8.8(rm stat.) pm 2.5(rm syst.)]$$~MeV, respectively, and the product branching fraction is $${cal B}(bar{B}^{0} to Xi_c(2930)^{+} bar{Lambda}_{c}^{-})$$ $${cal B}(Xi_c(2930)^{+}to bar{K}^{0} Lambda_{c}^{+})=[2.37 pm 0.51 (rm stat.)pm 0.31(rm syst.)]times 10^{-4}$$. We also measure $${cal B}(bar{B}^{0} to bar{K}^{0} Lambda_{c}^{+} bar{Lambda}_{c}^{-}) = [3.99 pm 0.76(rm stat.) pm 0.51(rm syst.)] times 10^{-4}$$ with greater precision than previous experiments, and present the results of a search for the charmonium-like state $$Y(4660)$$ and its spin partner, $$Y_{eta}$$, in the $$Lambda_{c}^{+}bar{Lambda}_{c}^{-}$$ invariant mass spectrum. No clear signals of the $$Y(4660)$$ or $$Y_{eta}$$ 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 $$(772pm11)times 10^{6} Bbar{B}$$ pairs collected at the $$Upsilon(4S)$$ resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.

論文

Measurement of $$cos{2beta}$$ in $$B^{0} to D^{(*)} h^{0}$$ with $$D to K_{S}^{0} pi^{+} pi^{-}$$ decays by a combined time-dependent Dalitz plot analysis of $$B_{A}B_{AR}$$ and Belle data

足立 一郎*; 谷田 聖; Belle Collaboration*; 他406名*

Physical Review D, 98(11), p.112012_1 - 112012_29, 2018/11

https://doi.org/10.1103/PhysRevD.98.112012
 被引用回数：1 パーセンタイル：64.74(Astronomy & Astrophysics)

We report measurements of $$sin{2beta}$$ and $$cos{2beta}$$ from a time-dependent Dalitz plot analysis of $$B^{0} to D^{(*)} h^{0}$$ with $$D to K_{S}^{0} pi^{+} pi^{-}$$ decays, where the light unflavored and neutral hadron $$h^{0}$$ is a $$pi^{0}$$, $$eta$$, or $$omega$$ meson. The analysis is performed with a combination of the final data sets of the BABAR and Belle experiments containing $$471 times 10^{6}$$ and $$772 times 10^{6}$$ $$Bbar{B}$$ pairs collected at the $$Upsilonleft(4Sright)$$ resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. We measure $$sin{2beta} = 0.80 pm 0.14 ,(rm{stat.}) pm 0.06 ,(rm{syst.}) pm 0.03 ,(rm{model})$$ and $$cos{2beta} = 0.91 pm 0.22 ,(rm{stat.}) pm 0.09 ,(rm{syst.}) pm 0.07 ,(rm{model})$$. The result for the direct measurement of the angle is $$beta = left( 22.5 pm 4.4 ,(rm{stat.}) pm 1.2 ,(rm{syst.}) pm 0.6 ,(rm{model}) right)^{circ}$$. The last quoted uncertainties are due to the composition of the $$D^{0} to K_{S}^{0} pi^{+} pi^{-}$$ decay amplitude model, which is newly established by a Dalitz plot amplitude analysis of a high-statistics $$e^{+}e^{-} to cbar{c}$$ data sample as part of this analysis. We find the first evidence for $$cos2beta>0$$ at the level of $$3.7$$ standard deviations. The measurement excludes the trigonometric multifold solution $$pi/2 - beta = (68.1 pm 0.7)^{circ}$$ at the level of $$7.3$$ standard deviations and therefore resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle. The hypothesis of $$beta = 0^{circ}$$ is ruled out at the level of $$5.1$$ standard deviations, and thus $$CP$$ violation is observed in $$B^{0} to D^{(*)} h^{0}$$ decays.

論文

Observation of $$e^+e^-topi^+pi^-pi^0chi_{b1,2}(1P)$$ and search for $$e^+e^-tophichi_{b1,2}(1P)$$ at $$sqrt{s}$$ = 10.96 - 11.05 GeV

Yin, J. H.*; 谷田 聖; Belle Collaboration*; 他189名*

Physical Review D, 98(9), p.091102_1 - 091102_9, 2018/11

https://doi.org/10.1103/PhysRevD.98.091102
 パーセンタイル：100(Astronomy & Astrophysics)

We report searches for the processes $$e^+e^-topi^+pi^-pi^0chi_{bJ}$$ and $$e^+e^-tophichi_{bJ}$$ (J=1,2) in the vicinity of the $$Upsilon(11020)$$ resonance using energy scan data collected by the Belle experiment at the KEKB collider. We observe $$e^+e^-to pi^+pi^-pi^0chi_{b1}$$ and find evidence for $$e^+e^-to omegachi_{b2}$$ processes for data with center-of-mass energies from 10.96 to 11.05~GeV for the first time. The statistical significance for $$pi^+pi^-pi^0chi_{b1}$$ and $$omegachi_{b2}$$ are $$6.1sigma$$ and $$4.0sigma$$, respectively. We investigate energy dependence of the $$e^+e^-topi^+pi^-pi^0chi_{bJ}$$ cross section and find that it is consistent with production of $$Upsilon(10860)$$ and $$Upsilon(11020)$$ resonances without significant non-resonant contribution. Assuming $$e^+e^-to pi^+pi^-pi^0chi_{bJ}$$ proceeds via $$Upsilon(10860)$$ and $$Upsilon(11020)$$, the branching fraction $$mathcal{B}(Upsilon(11020)topi^+pi^-pi^0chi_{bJ})=(8.6pm4.1pm6.1^{+4.5}_{-2.5})times10^{-3}$$ is measured for the first time, where the first error is statistical, the second is systematic, and the third from the branching fraction of $$Upsilon(11020)to e^+e^-$$. The signals for $$e^+e^-to phichi_{bJ}$$ are not significant, and the upper limits of the Born cross sections at the 90% confidence level are $$0.6$$ and $$1.0$$~pb for $$e^+e^-to phichi_{b1}$$ and $$phichi_{b2}$$, respectively, for center-of-mass energies from 10.96 to 11.05 GeV.

論文

Observation of $$e^+e^- to gamma chi_{c1}$$ and search for $$e^+e^- to gamma chi_{c0}, gamma chi_{c2}$$, and $$gammaeta_c$$ at $$sqrt{s}$$ near 10.6 GeV at Belle

Jia, S.*; 谷田 聖; Belle Collaboration*; 他191名*

Physical Review D, 98(9), p.092015_1 - 092015_8, 2018/11

https://doi.org/10.1103/PhysRevD.98.092015
 パーセンタイル：100(Astronomy & Astrophysics)

Using data samples of 89.5~fb$$^{-1}$$, 711.0~fb$$^{-1}$$, and 121.4~fb$$^{-1}$$ collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider at center-of-mass energies 10.52 GeV, 10.58 GeV, and 10.867 GeV, respectively, we study the exclusive reactions $$e^+e^-togammachi_{cJ}$$ ($$J = 0,~1,~2$$) and $$e^+e^-togammaeta_c$$. A significant $$gamma chi_{c1}$$ signal is observed for the first time at $$sqrt{s}=10.58$$ GeV with a significance of $$5.1sigma$$ including systematic uncertainties. No significant excesses for $$gamma chi_{c0}$$, $$gamma chi_{c2}$$, and $$gamma eta_c$$ final states are found, and we set 90% credibility level upper limits on the Born cross sections ($$sigma_{rm B}$$) at 10.52 GeV, 10.58 GeV, and 10.867~GeV. Together with cross sections measured by BESIII at lower center-of-mass energies, the energy dependency of $$sigma_{rm B}(e^+e^-togammachi_{c1})$$ is obtained.

論文

Search for the lepton-flavor-violating decay $$B^{0}to K^{ast 0} mu^{pm} e^{mp}$$

Sandilya, S.*; 谷田 聖; Belle Collaboration*; 他211名*

Physical Review D, 98(7), p.071101_1 - 071101_8, 2018/10

https://doi.org/10.1103/PhysRevD.98.071101
 被引用回数：1 パーセンタイル：64.74(Astronomy & Astrophysics)

We have searched for the lepton-flavor-violating decay $$B^{0}to K^{ast 0} mu^{pm} e^{mp}$$ using a data sample of 711 fb$$^{-1}$$ that contains $$772 times 10^{6}$$ $$Bbar{B}$$ pairs. The data were collected near the $$Upsilon (4S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^{+}e^{-}$$ collider. No signals were observed, and we set 90% confidence level upper limits on the branching fractions of $${cal B}(B^{0}to K^{ast 0} mu^{+} e^{-}) < 1.2times 10^{-7}$$, $${cal B}(B^{0}to K^{ast 0} mu^{-} e^{+}) < 1.6times 10^{-7}$$, and, for both decays combined, $${cal B}(B^{0}to K^{ast 0} mu^{pm} e^{mp}) < 1.8times 10^{-7}$$. These are the most stringent limits on these decays to date.

論文

Measurement of $$eta_c(1S)$$, $$eta_c(2S)$$, and nonresonant $$eta' pi^+ pi^-$$ production via two-photon collisions

Xu, Q. N.*; 谷田 聖; Belle Collaboration*; 他176名*

Physical Review D, 98(7), p.072001_1 - 072001_17, 2018/10

https://doi.org/10.1103/PhysRevD.98.072001
 パーセンタイル：100(Astronomy & Astrophysics)

We report the measurement of $$gamma gamma to eta_c(1S)$$, $$eta_c(2S) to eta' pi^+ pi^-$$ with $$eta'$$ decays to $$gamma rho$$ and $$eta pi^+ pi^-$$ using 941 fb$$^{-1}$$ of data collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider. The $$eta_c(1S)$$ mass and width are measured to be $$M = [2984.6pm0.7 (stat.)pm2.2 (syst.)]$$ MeV/$$c^{2}$$ and $$Gamma = [30.8^{+2.3}_{-2.2}~(stat.) pm 2.5~(syst.)]$$ MeV, respectively. First observation of $$eta_c(2S) to eta' pi^+ pi^-$$ with a significance of $$5.5sigma$$ including systematic error is obtained, and the $$eta_c(2S)$$ mass is measured to be $$M = [3635.1pm3.7~(stat.)pm2.9~(syst.)]$$ MeV/$$c^{2}$$. The products of the two-photon decay width and branching fraction $$(B)$$ of decays to $$eta'pi^+ pi^-$$ are determined to be $$Gamma_{gamma gamma}B = [65.4pm2.6~(stat.)pm6.9~(syst.)]$$ eV for $$eta_c(1S)$$ and $$[5.6^{+1.2}_{-1.1}~(stat.)pm1.1~(syst.)]$$ eV for $$eta_c(2S)$$. A new decay mode for the $$eta_c(1S)$$ to $$eta'f_0(2080)$$ with $$f_0(2080) to pi^+ pi^-$$ is observed with a statistical significance of $$20sigma$$. The $$f_0(2080)$$ mass and width are determined to be $$M = [2083^{+63}_{-66}~(stat.)pm 32~(syst.)]$$ MeV/$$c^{2}$$ and $$Gamma = [178^{+60}_{-178}~(stat.) pm 55~(syst.)]$$ MeV. The cross sections for $$gamma gamma to eta' pi^+ pi^-$$ and $$eta'f_{2}(1270)$$ are measured for the first time.

論文

Inclusive study of bottomonium production in association with an $$eta $$ meson in $$e^+e^-$$ annihilations near $$Upsilon (5S)$$

Tamponi, U.*; 谷田 聖; Belle Collaboration*; 他174名*

European Physical Journal C, 78(8), p.633_1 - 633_10, 2018/08

https://doi.org/10.1140/epjc/s10052-018-6086-4

We study bottomonium production in association with an $$eta$$ meson in $$e^+e^-$$ annihilations near the $$Upsilon(5S)$$, at a center of mass energy of $$sqrt{s}=10.866,$$GeV. The results are based on the $$121.4,$$fb$$^{-1}$$ data sample collected by the Belle experiment at the asymmetric energy KEKB collider. Only the $$eta$$ meson is reconstructed and the missing-mass spectrum of $$eta$$ candidates is investigated. We observe the $$e^+e^-toetaUpsilon_J(1D)$$ process and find evidence for the $$e^+e^-toetaUpsilon(2S)$$ process, while no significant signals of $$Upsilon(1S)$$, $$h_b(1P)$$, nor $$h_b(2P)$$ are found. Cross sections for the studied processes are reported.

論文

Observation of an excited $$Omega^-$$ Baryon

Yelton, J.*; 谷田 聖; Belle Collaboration*; 他190名*

Physical Review Letters, 121(5), p.052003_1 - 052003_7, 2018/08

https://doi.org/10.1103/PhysRevLett.121.052003
 被引用回数：7 パーセンタイル：6.69(Physics, Multidisciplinary)

Using data recorded with the Belle detector, we observe a new excited hyperon, an $$Omega^{*-}$$ candidate decaying into $$Xi^0K^-$$ and $$Xi^-K^0_S$$ with a mass of $$2012.4pm0.7 {rm (stat)pm 0.6 (rm syst)} {rm MeV}/c^2$$ and a width of $$Gamma=6.4^{+2.5}_{-2.0} {rm(stat)}pm1.6 {rm(syst)} {rm MeV}$$. The $$Omega^{*-}$$ is seen primarily in $$Upsilon(1S), Upsilon(2S)$$, and $$Upsilon(3S)$$ decays.

論文

Observation of $$Upsilon(4S)to eta' Upsilon(1S)$$

Guido, E.*; 谷田 聖; Belle Collaboration*; 他168名*

Physical Review Letters, 121(6), p.062001_1 - 062001_7, 2018/08

https://doi.org/10.1103/PhysRevLett.121.062001
 パーセンタイル：100(Physics, Multidisciplinary)

We report the first observation of the hadronic transition $$Upsilon(4S)toeta'Upsilon(1S)$$, using 496 fb$$^{-1}$$ data collected at the $$Upsilon(4S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^{+}e^{-}$$ collider. We reconstruct the $$eta'$$ meson through its decays to $$rho^0gamma$$ and to $$pi^+pi^-eta$$, with $$etatogammagamma$$. We measure: $${cal B}(Upsilon(4S)toeta'Upsilon(1S))=(3.43pm 0.88 {rm(stat.)} pm 0.21 {rm(syst.)})times10^{-5}$$, with a significance of 5.7$$sigma$$.

論文

Measurement of the branching fraction of $$B rightarrow D^{(*)}pi ellnu$$ at Belle using hadronic tagging in fully reconstructed events

Vossen, A.*; 谷田 聖; Belle Collaboration*; 他164名*

Physical Review D, 98(1), p.012005_1 - 012005_9, 2018/07

https://doi.org/10.1103/PhysRevD.98.012005
 パーセンタイル：100(Astronomy & Astrophysics)

We report a measurement of the branching fraction of the decay $$B rightarrow D^{(*)}pi ellnu$$. The analysis uses 772$$times 10^6$$ $$Bbar{B}$$ pairs produced in $$e^+e^-rightarrow Upsilon(4S)$$ data recorded by the Belle experiment at the KEKB asymmetric-energy $$e^+e^-$$ collider. The tagging $$B$$ meson in the decay is fully reconstructed in a hadronic decay mode. On the signal side, we reconstruct the decay $$B rightarrow D^{(*)}pi ellnu$$ $$(ell=e,mu)$$. The measured branching fractions are $$mathcal{B}(B^+ rightarrow D^-pi^+ ell^+nu)$$ = [4.55 $$pm$$ 0.27 (stat.) $$pm$$ 0.39 (syst.)]$$times 10^{-3}$$, $$mathcal{B}(B^0 rightarrow bar{D}^0pi^- ell^+nu)$$ = [4.05 $$pm$$ 0.36 (stat.) $$pm$$ 0.41 (syst.)]$$times 10^{-3}$$, $$mathcal{B}(B^+ rightarrow D^{*-}pi^+ ell^+nu)$$ = [6.03 $$pm$$ 0.43 (stat.) $$pm$$ 0.38 (syst.)]$$times 10^{-3}$$, and $$mathcal{B}(B^0 rightarrow bar{D}^{*0}pi^- ell^+nu)$$ = [6.46 $$pm$$ 0.53 (stat.) $$pm$$ 0.52 (syst.)]$$times 10^{-3}$$. These are in good agreement with the current world average values.

論文

Search for $$B^{-}tomu^{-}barnu_mu$$ decays at the Belle experiment

Sibidanov, A.*; 谷田 聖; Belle Collaboration*; 他187名*

Physical Review Letters, 121(3), p.031801_1 - 031801_8, 2018/07

https://doi.org/10.1103/PhysRevLett.121.031801
 被引用回数：3 パーセンタイル：20.01(Physics, Multidisciplinary)

We report the result of a search for the decay $$B^{-}tomu^{-}barnu_mu$$. 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 $$B$$-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 $${cal B}(B^{-}tomu^{-}barnu_mu) =(6.46 pm 2.22 pm 1.60) times10^{-7}$$ or a frequentist 90% confidence level interval on the $$B^{-}tomu^{-}barnu_mu$$ branching fraction of $$[2.9, 10.7]times 10^{-7}$$. This result is obtained from a 711 fb$$^{-1}$$ data sample that contains $$772 times 10^6$$ $$Bbar{B}$$ pairs, collected near the $$Upsilon(4S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^+ e^-$$ collider.

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