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論文

"$$K^-pp$$", a $$bar K$$-meson nuclear bound state, observed in $$^3$$He($$K^-,Lambda p)n$$ reactions

橋本 直; 谷田 聖; 他67名*

Physics Letters B, 789, p.620 - 625, 2019/02

 パーセンタイル:100(Astronomy & Astrophysics)

$$^{3}{rm He}(K^-, , Lambda p)n$$における$$Lambda p$$不変質量分布において$$m_K + 2m_p$$、つまり$$K^-$$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。$$q$$ = 350$$sim$$650MeV/$$c$$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($$overline{K}N rightarrow overline{K}N$$)に続いて残りの2各紙に吸収される反応($$overline{K}NN rightarrow Lambda N$$)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$$B_{rm {it Kpp}} = 47 pm 3 , (stat.) ,^{+3}_{-6},(sys.)$$ MeV、幅$$Gamma_{rm {it Kpp}} = 115 pm 7 , (stat.),^{+10}_{-20} ,(sys.)$$ MeV、そして$$S$$波ガウス形状因子パラメータ$$Q_{rm {it Kpp}} = 381 pm 14 , (stat.),^{+57}_{-0} ,(sys.)$$MeV/$$c$$という値が"$$K^-pp$$"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。

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

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

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

 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

 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

 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

 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

 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

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

Low-momentum direct-photon measurement in Cu + Cu collisions at $$sqrt{s_{_{NN}}}=200$$ GeV

Adare, 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448名*

Physical Review C, 98(5), p.054902_1 - 054902_11, 2018/11

 パーセンタイル:100(Physics, Nuclear)

We have measured direct photons for $$p_T< 5~$$GeV/$$c$$ in minimum bias and 0% - 40% most central events at midrapidity for Cu$$+$$Cu collisions at $$sqrt{s_{_{NN}}}=200$$ GeV. The $$e^{+}e^{-}$$ contribution from quasi-real direct virtual photons has been determined as an excess over the known hadronic contributions in the $$e^{+}e^{-}$$ mass distribution. A clear enhancement of photons over the binary scaled $$p$$$$+$$$$p$$ fit is observed for $$p_T < 4$$ GeV/$$c$$ in Cu$$+$$Cu data. The $$p_T$$ spectra are consistent with the Au$$+$$Au data covering a similar number of participants. The inverse slopes of the exponential fits to the excess after subtraction of the $$p$$$$+$$$$p$$ baseline are 285$$pm$$53(stat)$$pm$$57(syst)~MeV/$$c$$ and 333$$pm$$72(stat)$$pm$$45(syst)~MeV/$$c$$ for minimum bias and 0% - 40% most central events, respectively. The rapidity density, $$dN/dy$$, of photons demonstrates the same power law as a function of $$dN_{rm ch}/deta$$ observed in Au$$+$$Au at the same collision energy.

論文

Production of $$pi^0$$ and $$eta$$ mesons in Cu+Au collisions at $$sqrt{s_{_{NN}}}$$=200 GeV

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

 被引用回数:1 パーセンタイル:49.68(Physics, Nuclear)

Production of $$pi^0$$ and $$eta$$ mesons has been measured at midrapidity in Cu$$+$$Au collisions at $$sqrt{s_{_{NN}}}$$=200 GeV. Measurements were performed in $$pi^0(eta)rightarrowgammagamma$$ decay channel in the 1(2)-20 GeV/$$c$$ transverse momentum range. A strong suppression is observed for $$pi^0$$ and $$eta$$ meson production at high transverse momentum in central Cu$$+$$Au collisions relative to the $$p$$$$+$$$$p$$ results scaled by the number of nucleon-nucleon collisions. In central collisions the suppression is similar to Au$$+$$Au with comparable nuclear overlap. The $$eta/pi^0$$ ratio measured as a function of transverse momentum is consistent with $$m_T$$-scaling parameterization down to $$p_T=$$2 GeV/$$c$$, its asymptotic value is constant and consistent with Au$$+$$Au and $$p$$$$+$$$$p$$ 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 $$e^+e^-$$ collisions in a range of collision energies $$sqrt{s_{_{NN}}}=$$ 3-1800 GeV. This suggests that the quark-gluon-plasma medium produced in Cu$$+$$Cu collisions either does not affect the jet fragmentation into light mesons or it affects the $$pi^0$$ and $$eta$$ the same way.

論文

Measurement of $$phi$$-meson production at forward rapidity in $$p+p$$ collisions at $$sqrt{s}=510$$ GeV and its energy dependence from $$sqrt{s}=200$$ GeV to 7 TeV

Adare, 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351名*

Physical Review D, 98(9), p.092006_1 - 092006_13, 2018/11

 パーセンタイル:100(Astronomy & Astrophysics)

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section of $$phi$$(1020) meson production at forward rapidity in $$p$$$$+$$$$p$$ collisions at $$sqrt{s}=$$510 GeV via the dimuon decay channel. The integrated cross section in the rapidity and $$p_T$$ ranges $$1.2 < |y| < 2.2$$ and $$2 < p_T < 7$$ GeV/$$c$$ is $$sigma_phi=2.79 pm 0.20,{rm (stat)} pm 0.17,{rm (syst)} pm 0.34, {rm (norm)} times 10^{-2}$$~mb. The energy dependence of $$sigma_phi$$ ($$1.2 < |y|<2.2$$; $$2<p_T<5$$ GeV/$$c$$) is studied using the PHENIX measurements at $$sqrt{s}=$$200 and 510 GeV and the Large-Hadron-Collider measurements at $$sqrt{s}=$$2.76 and 7 TeV. The experimental results are compared to various event generator predictions (pythia6, pythia8, phojet, ampt, epos3, and epos-lhc).

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

 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

 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

 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

Pseudorapidity dependence of particle production and elliptic flow in asymmetric nuclear collisions of $$p$$+Al, $$p$$+Au, $$d$$+Au, and $$^{3}$$He+Au at $$sqrt{s_{_{NN}}}$$ = 200 GeV

Adare, A.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他362名*

Physical Review Letters, 121(22), p.222301_1 - 222301_8, 2018/11

 被引用回数:3 パーセンタイル:29.91(Physics, Multidisciplinary)

Asymmetric nuclear collisions of $$p$$+Al, $$p$$+Au, $$d$$+Au, and $$^{3}$$He+Au at $$sqrt{s_{_{NN}}}$$ = 200 GeV provide an excellent laboratory for understanding particle production, as well as exploring interactions among these particles after their initial creation in the collision. We present measurements of charged hadron production $$dN_{rm ch}/deta$$ in all such collision systems over a broad pseudorapidity range and as a function of collision multiplicity. A simple wounded quark model is remarkably successful at describing the full data set. We also measure the elliptic flow $$v_{2}$$ over a similarly broad pseudorapidity range. These measurements provide key constraints on models of particle emission and their translation into flow.

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

 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

 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

Nonperturbative transverse-momentum-dependent effects in dihadron and direct photon-hadron angular correlations in $$p+p$$ collisions at $$sqrt{s}=200$$ GeV

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

 被引用回数:1 パーセンタイル:64.74(Astronomy & Astrophysics)

Dihadron and isolated direct photon-hadron angular correlations are measured in $$p$$$$+$$$$p$$ collisions at $$sqrt{s}=200$$ GeV. The correlations are sensitive to nonperturbative initial-state and final-state transverse momentum $$k_T$$ and $$j_T$$ in the azimuthal nearly back-to-back region $$Deltaphisimpi$$. 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 $$p_{rm out}$$, 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 $$sqrt{s}=510$$ GeV. The nonperturbative jet widths also appear to increase with $$sqrt{s}$$ at a similar $$x_T$$, which is qualitatively consistent to similar measurements in Drell-Yan interactions.

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, p.633_1 - 633_10, 2018/08

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

Cross section and longitudinal single-spin asymmetry $$A_L$$ for forward $$W^{pm}rightarrowmu^{pm}nu$$ production in polarized $$p$$$$+$$$$p$$ collisions at $$sqrt{s}=510$$ GeV

Adare, 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423名*

Physical Review D, 98(3), p.032007_1 - 032007_14, 2018/08

We have measured the cross section and single spin asymmetries from forward $$W^{pm}rightarrowmu^{pm}nu$$ production in longitudinally polarized $$p$$$$+$$$$p$$ collisions at $$sqrt{s}=510$$ GeV using the PHENIX detector at the Relativistic Heavy Ion Collider. The cross sections are consistent with previous measurements at this collision energy, while the most forward and backward longitudinal single spin asymmetries provide new insights into the sea quark helicities in the proton. The charge of the $$W$$ bosons provides a natural flavor separation of the participating partons.

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