Publications (505)223.63 Total impact
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Article: Evidence for B_s^0 -> Lambda_c^+ Lambda-bar pi^-
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ABSTRACT: Using 121.4 fb^{-1} of data collected with the Belle detector at the Y(5S) resonance at the KEKB asymmetric-energy e^+e^- collider, we report evidence for the B_s^0 -> Lambda_c^+ Lambda-bar pi^- decay mode with a measured branching fraction (3.6 +- 1.1[stat.] {+0.3 -0.5}[syst.] +- 0.9[Lambda_c^+] +- 0.7[N_{Bs}]) * 10^{-4} and a significance of 4.4 standard deviations. This is the first evidence for a baryonic B_s^0 decay.04/2013; -
Article: Evidence of a new narrow resonance decaying to $\chi_{c1}\gamma$ in $B \to \chi_{c1} \gamma K$
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ABSTRACT: We report measurements of $B \to \chi_{c1} \gamma K$ and $\chi_{c2} \gamma K$ decays using $772 \times 10^{6}$ $B\bar{B}$ events collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. Evidence of a new resonance in the $\chi_{c1} \gamma$ final state is found with a statistical significance of $3.8 \sigma$. This state has a mass of $3823.1 \pm 1.8 {(stat)} \pm 0.7 {(syst)}$ MeV/$c^2$, a value that is consistent with theoretical expectations for the previously unseen $1^3 D_2$ $c\bar{c}$ meson. We find no other narrow resonance and set upper limits on the branching fractions of the $X(3872) \to \chi_{c1} \gamma$ and $\chi_{c2} \gamma$ decays.04/2013; -
Article: Study of $e^+ e^- \to \pi^+ \pi^- J/\psi$ and Observation of a Charged Charmonium-like State at Belle
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ABSTRACT: The cross section for $e^+ e^- \to \pi^+ \pi^- J/\psi$ between 3.8 GeV and 5.5 GeV is measured with a 967 fb$^{-1}$ data sample collected by the Belle detector at or near the $\Upsilon(nS)$ ($n = 1,\ 2,\ ...,\ 5$) resonances. The Y(4260) state is observed, and its resonance parameters are determined. In addition, an excess of $\pi^+ \pi^- J/\psi$ production around 4 GeV is observed. This feature can be described by a Breit-Wigner parameterization with properties that are consistent with the Y(4008) state that was previously reported by Belle. In a study of $Y(4260) \to \pi^+ \pi^- J/\psi$ decays, a structure is observed in the $M(\pi^\pm\jpsi)$ mass spectrum with $5.2\sigma$ significance, with mass $M=(3894.5\pm 6.6\pm 4.5) {\rm MeV}/c^2$ and width $\Gamma=(63\pm 24\pm 26)$ MeV/$c^{2}$, where the errors are statistical and systematic, respectively. This structure can be interpreted as a new charged charmonium-like state.03/2013; -
Article: Search for B -> h(*) nu nubar with the full Belle Y(4S) data sample
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ABSTRACT: We report a search for the rare decays B -> h(*) nu nubar, where h(*) stands for K+, Ks0, K*+, K*0, pi+, pi0, rho+, rho0 and phi. The results are obtained from a 711 fb-1 data sample that contains 772 million BB pairs collected at the Y(4S) resonance with the Belle detector at the KEKB e+e- collider. We search for signal candidates by fully reconstructing a hadronic decay of the accompanying B meson and requiring a single h(*) meson left on the signal side. No significant signal is observed and we set upper limits on the branching fractions at 90% confidence level. The measurements of B+ -> K*+ nu nubar, B+ -> pi+ nu nubar, B0 -> pi0 nu nubar and B0 -> rho^0 nu nubar provide the world's currently most restrictive limits.03/2013; -
Article: Measurement of the CP Violation Parameters in B0 -> pi+ pi- Decays
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ABSTRACT: We present a measurement of the time-dependent CP violation parameters in B0 -> pi+ pi- decays. The results are obtained from the final data sample containing 772 million BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain the CP violation parameters Acp = +0.33 +/- 0.06 (stat) +/- 0.03 (syst) and Scp = -0.64 +/- 0.08 (stat) +/- 0.03 (syst), where Acp and Scp represent direct and mixing-induced CP violation, respectively. From an isospin analysis including results from other Belle measurements, we rule out 23.8 < phi2 < 66.8 degrees at the 1 sigma level.02/2013; -
Article: Precision measurement of charged pion and kaon multiplicities in electron-positron annihilation at Q = 10.52 GeV
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ABSTRACT: Precise measurements of inclusive multiplicities of charged pions and kaons produced in electron-positron annihilation have been carried out at a center-of-mass energy of 10.52 GeV. The measurements were performed with the Belle detector at the KEKB electron-positron collider using a data sample containing 113 million e+e- -> qqbar events, where q={u,d,s,c}. We present charge-integrated multiplicities 1/N_evts * dN_h+-/dz for h+- = pi+-, K+- as a function of the relative hadron energy z = 2*E_h / sqrt{s} from 0.2 to 0.98 (0.97) for pions (kaons). The combined statistical and systematic uncertainties for pi+- (K+-) are 4% (5%) at z ~ 0.6 and 18% (51%) at z ~ 0.9. The multiplicities are the first measurements of the z-dependence of pion and kaon multiplicities for z > 0.7 as well as the first precision multiplicity measurements at a center-of-mass energy far below the Z^0 resonance used by the experiments at LEP and SLC.01/2013; -
Article: Measurement of the inclusive semileptonic branching fraction Bf(B_s^0 -> X^- l^+ nu) at Belle
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ABSTRACT: We report a measurement of the inclusive semileptonic B_s^0 branching fraction in a 121 fb^{-1} data sample collected near the Upsilon(5S) resonance with the Belle detector at the KEKB asymmetric energy e^+ e^- collider. Events containing B_s^0 pairs are selected by reconstructing a tag side D_s^+ and identifying a signal side lepton l^+ (l = e, mu) that is required to have the same-sign charge to ensure that both originate from different B_s^0 mesons. The B_s^0 -> X^- l^+ nu branching fraction is extracted from the ratio of the measured yields of D_s^+ mesons and D_s^+ l^+ pairs and the known production and branching fractions. The inclusive semileptonic branching fraction is measured to be [10.6 +/- 0.5(stat) +/- 0.7(syst)] %.12/2012; -
Article: Search for CP Violation in the Decay $D^+\rightarrow K^0_S K^+$
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ABSTRACT: We search for CP violation in the decay $D^+\rightarrow K^0_S K^+$ using a data sample with an integrated luminosity of 977 fb$^{-1}$ collected with the Belle detector at the KEKB $e^+e^-$ asymmetric-energy collider. No CP violation has been observed and the CP asymmetry in $D^+\rightarrow K^0_S K^+$ decay is measured to be $(-0.25\pm0.28\pm0.14)%$, which is the most sensitive measurement to date. After subtracting CP violation due to $K^0-\bar{K}^0$ mixing, the CP asymmetry in $D^+\rightarrow\bar{K}^0 K^+$ decay is found to be $(+0.08\pm0.28\pm0.14)%$.12/2012; -
Article: Evidence for the η_{b}(2S) and Observation of h_{b}(1P)→η_{b}(1S)γ and h_{b}(2P)→η_{b}(1S)γ
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ABSTRACT: We report the first evidence for the η_{b}(2S) using the h_{b}(2P)→η_{b}(2S)γ transition and the first observation of the h_{b}(1P)→η_{b}(1S)γ and h_{b}(2P)→η_{b}(1S)γ transitions. The mass and width of the η_{b}(1S) and η_{b}(2S) are measured to be m_{η_{b}(1S)}=(9402.4±1.5±1.8) MeV/c^{2}, m_{η_{b}(2S)}=(9999.0±3.5_{-1.9}^{+2.8}) MeV/c^{2}, and Γ_{η_{b}(1S)}=(10.8_{-3.7-2.0}^{+4.0+4.5}) MeV. We also update the h_{b}(1P) and h_{b}(2P) mass measurements. We use a 133.4 fb^{-1} data sample collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider.Physical Review Letters 12/2012; 109(23):232002. · 7.37 Impact Factor -
Article: First observation of CP violation and improved measurement of the branching fraction and polarization of B0 -> D*+ D*- decays
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ABSTRACT: We report the measurement of the branching fraction, the polarization, and the parameters of the time-dependent CP violation in B0 -> D*+ D*- decays using a data sample of 772 million BB pairs, collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain a branching fraction of B = (7.82 +- 0.38 +- 0.63) x10^{-4}, a CP-odd fraction of R_\perp = 0.138 +- 0.024 +- 0.006 and, additionally, a fraction of the longitudinal component in the transversity base of R_0 = 0.624 +- 0.029 +- 0.011. The measured values of the parameters of the CP violation are S_{D*+ D*-} = -0.79 +- 0.13 +- 0.03 and A_{D*+ D*-} = 0.15 +- 0.08 +- 0.04.07/2012; -
Article: Evidence for CP Violation in the Decay D^{+}→K_{S}^{0}π^{+}.
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ABSTRACT: We observe evidence for CP violation in the decay D^{+}→K_{S}^{0}π^{+} using a data sample with an integrated luminosity of 977 fb^{-1} collected by the Belle detector at the KEKB e^{+}e^{-} asymmetric-energy collider. The CP asymmetry in the decay is measured to be (-0.363±0.094±0.067)%, which is 3.2 standard deviations away from zero, and is consistent with the expected CP violation due to the neutral kaon in the final state.Physical Review Letters 07/2012; 109(2):021601. · 7.37 Impact Factor -
Article: Search for $B^{0}$ decays to invisible final states at Belle
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ABSTRACT: We report a search for $B^{0}$ decays into invisible final states using a data sample of $657 \times 10^{6}$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^{+}e^{-}$ collider. The signal is identified by fully reconstructing a hadronic decay of the accompanying $B$ meson and requiring no other particles in the event. No significant signal is observed, and we obtain an upper limit of $1.3 \times 10^{-4}$ at the 90% confidence level for the branching fraction of invisible $B^{0}$ decay.06/2012; -
Article: First measurement of ϕ3 with a model-independent Dalitz plot analysis of B±→DK±, D→KS0π+π- decay
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ABSTRACT: We present the first measurement of the angle ϕ3 of the unitarity triangle using a model-independent Dalitz plot analysis of B±→DK±, D→KS0π+π- decays. The method uses, as input, measurements of the strong phase of the D→KS0π+π- amplitude from the CLEO Collaboration. The result is based on the full data set of 772×106 BB̅ pairs collected by the Belle experiment at the Υ(4S) resonance. We obtain ϕ3=(77.3-14.9+15.1±4.1±4.3)° and the suppressed amplitude ratio rB=0.145±0.030±0.010±0.011. Here the first error is statistical, the second is the experimental systematic uncertainty, and the third is the error due to the precision of the strong-phase parameters obtained by CLEO.Phys. Rev. D. 06/2012; 85(11). -
Article: Search for Lepton-Flavor-Violating and Lepton-Number-Violating tau to lhh' Decay Modes
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ABSTRACT: We search for lepton-flavor-violating and lepton-number-violating tau decays into a lepton (l = electron or muon) and two charged mesons (h, h' = pion or Kaon) using 854 fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We obtain 90% confidence level upper limits on the tau to lhh' branching fractions in the range (2.0-8.4)*10^{-8}. These results improve upon our previously published upper limits by factors of about 1.8 on average.06/2012; -
Article: First study of \eta_c, \eta(1760) and X(1835) production via \eta'\pi^+\pi^- final states in two-photon collisions
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ABSTRACT: The invariant mass spectrum of the \eta' \pi^+ \pi^- final state produced in two-photon collisions is obtained using a 673 fb^{-1} data sample collected in the vicinity of the \Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We observe a clear signal of the \eta_c and measure its mass and width to be M(\eta_c)=(2982.7 +- 1.8(stat) +- 2.2(syst) +- 0.3(model)) MeV/c^2 and \Gamma(\eta_c) = (37.8^{+5.8}_{-5.3}(stat) +- 2.8(syst) +- 1.4(model)) MeV/c^2. The third error is an uncertainty due to possible interference between the \eta_c and a non-resonant component. We also report the first evidence for \eta(1760) decay to \eta' \pi^+ \pi^-; we find two solutions for its parameters, depending on the inclusion or not of the X(1835), whose existence is of marginal significance in our data. From a fit to the mass spectrum using coherent X(1835) and \eta(1760) resonant amplitudes, we set a 90% confidence level upper limit on the product \Gamma_{\gamma\gamma} \BR (\eta' \pi^+ \pi^-) for the X(1835).06/2012; -
Article: Search for B -> phi pi decays
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ABSTRACT: We report on a search for the charmless decays $B^{+} \to\phi\pi^{+}$ and $B^{0} \to\phi \pi^{0}$ that are strongly suppressed in the Standard Model. The analysis is based on a data sample of $657 \times 10^6$ $B \bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We find no significant signal and set upper limits of $3.3 \times 10^{-7}$ for $B^{+} \to \phi \pi^{+}$ and $1.5 \times 10^{-7}$ for $B^0 \to \phi \pi^0$ at the 90% confidence level.06/2012; -
Article: Evidence for the eta_b(2S) and observation of h_b(1P) -> eta_b(1S) gamma and h_b(2P) -> eta_b(1S) gamma
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ABSTRACT: We report the first evidence for the eta_b(2S) using the h_b(2P)->eta_b(2S)gamma transition and the first observation of the h_b(1P)->eta_b(1S)gamma and h_b(2P)->eta_b(1S)gamma transitions. The mass and width of the eta_b(1S) and eta_b(2S) are measured to be m_etab(1S)=(9402.4+-1.5+-1.8)MeV/c^2, m_etab(2S)=(9999.0+-3.5 +2.8-1.9)MeV/c^2 and Gamma_etab(1S)=(10.8 +4.0-3.7 +4.5-2.0)MeV. We also update the h_b(1P) and h_b(2P) mass measurements. We use a 133.4/fb data sample collected at energies near the Upsilon(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.05/2012; -
Article: Measurement of Branching Fraction and First Evidence of CP Violation in B0 --> a1+-(1260) pi-+ Decays
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ABSTRACT: We present a measurement of the branching fraction and time-dependent CP violation parameters in B0 --> a_1^+-(1260) pi^-+ decays. The results are obtained from the final data sample containing 772x10^6 BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We also measure an upper limit on the product branching fraction for a possible decay with the same final state B0 --> a_2^+-(1320) pi^-+. In a time-dependent measurement to extract CP asymmetries, we find evidence of mixing-induced CP violation in B0 --> a_1^+-(1260) pi^-+ decays with a 3.1 sigma significance and the rate where the a_1^+-(1260) does not contain the spectator quark is found to dominate the rate where it does at the 4.1 sigma level. However, there is no evidence for either time and flavor integrated direct CP violation or flavor-dependent direct CP violation.05/2012; -
Article: First observation of exclusive $\Upsilon(1S)$ and $\Upsilon(2S)$ decays into light hadrons
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ABSTRACT: Using samples of 102 million $\Upsilon(1S)$ and 158 million $\Upsilon(2S)$ events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the three-body final states $\phi K^+ K^-$, $\omega \pi^+ \pi^-$ and $K^{\ast 0}(892) K^- \pi^+ $, and to the two-body Vector-Tensor ($\phi f_2'(1525)$, $\omega f_2(1270)$, $\rho a_2(1320)$ and $K^{\ast 0}(892) \bar{K}_2^{\ast 0}(1430) $) and Axial-vector-Pseudoscalar ($K_1(1270)^+ K^-$, $K_1(1400)^+ K^- $ and $b_1(1235)^+ \pi^- $) pairs. Signals are observed for the first time in the $\Upsilon(1S) \to \phi K^+ K^-$, $\omega \pi^+ \pi^-$, $K^{\ast 0} K^- \pi^+$, $K^{\ast0} K_2^{\ast 0}$ and $\Upsilon(2S) \to \phi K^+ K^-$, $K^{\ast 0} K^- \pi^+$ decay modes. Branching fractions are determined for all the processes, while 90% confidence level upper limits are established on the branching fractions for the modes with a statistical significance less than $3\sigma$. The ratios of the branching fractions of $\Upsilon(2S)$ and $\Upsilon(1S)$ decays into the same final state are used to test a perturbative QCD prediction for OZI suppressed bottomonium decays.05/2012; -
Article: First observation of B(s)(0) → J/ψη and B(s)(0) → J/ψη'.
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ABSTRACT: We report first observations of B(s)(0) → J/ψη and B(s)(0) → J/ψη'. The results are obtained from 121.4 fb(-1) of data collected at the Υ(5S) resonance with the Belle detector at the KEKB e+ e- collider. We obtain the branching fractions B(B(s)(0) → J/ψη)=[5.10±0.50(stat)±0.25(syst)(-0.79)(+1.14)(N(B(s)(*) B(s)(*))]×10(-4), and B(B(s)(0) → J/ψη')=[3.71±0.61(stat)±0.18(syst)(-0.57)(+0.83)(N(B(s)(*) B(s)(*))]×10(-4). The ratio of the two branching fractions is measured to be (B(B(s) → J/ψη'))/(B(B(s) → J/ψη))=0.73±0.14(stat)±0.02(syst).Physical Review Letters 05/2012; 108(18):181808. · 7.37 Impact Factor
Top Journals
Institutions
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2012
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Novosibirsk State University
Novosibirsk, Novosibirskaya Oblast', Russia -
Institute for Theoretical and Experimental Physics
Moscow, Moscow, Russia -
University of Maribor
Maribor, Mestna Obcina Maribor, Slovenia -
National Taiwan University
- Department of Physics
Taipei, Taipei, Taiwan -
High Energy Accelerator Research Organization
Tsukuba, Ibaraki-ken, Japan
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2011–2012
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Korea University
Seoul, Seoul, South Korea -
Seoul National University
Seoul, Seoul, South Korea -
Tohoku University
- Research Center for Electron Photon Science
Sendai, Kagoshima-ken, Japan -
University of Illinois, Urbana-Champaign
Urbana, IL, USA -
Nara Women's University
Nara-shi, Nara, Japan -
Panjab University
Chandīgarh, Union Territory of Chandigarh, India
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1970–2012
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Jožef Stefan Institute
Ljubljana, Ljubljana, Slovenia
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2010
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Honolulu University
Honolulu, HI, USA -
University of Cincinnati
Cincinnati, OH, USA
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2003–2005
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Budker Institute of Nuclear Physics
Akademgorodok, Novosibirskaya Oblast', Russia
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2002–2003
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Aomori University
Aomori-shi, Aomori-ken, Japan
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1991
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University of Ljubljana
Ljubljana, Ljubljana, Slovenia
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