Publications (102)136.61 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 for the decay B0 --> K+K-pi0
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ABSTRACT: We report a search for charmless hadronic decays of neutral B mesons to the final state K+K-pi0. The results are based on a 711 fb^-1 data sample that contains 772x10^6 BB-bar pairs, and was collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find the first evidence for this decay with a significance of 3.5 standard deviations and measure its branching fraction as BF(B0 --> K+K-pi0) = [2.17 +/- 0.60(stat) +/- 0.24 (syst)]x10^-6.04/2013; -
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: Search for heavy neutrinos at Belle
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ABSTRACT: We report on a search for heavy neutrinos in B-meson decays. The results are obtained using a data sample that contains 772x10^6 BB-bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. No signal is observed and upper limits are set on mixing of heavy neutrinos with left-handed neutrinos of the Standard Model in the mass range 0.5 - 5.0 GeV/c^2.01/2013; -
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: Study of B^0 -> rho^0 rho^0 decays, implications for the CKM angle phi_2 and search for other four pion final states
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ABSTRACT: We present a study of the branching fraction of the decay B^0 -> rho^0 rho^0 and the fraction of longitudinally polarized \rho^0 mesons in this decay. The results are obtained from the final data sample containing $772 \times 10^{6}$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We find $166 \pm 59$ B^0 -> rho^0 rho^0 events, corresponding to a branching fraction of ${\cal B}(B^0 -> rho^0 rho^0) = (1.02\pm 0.30 (\rm stat) \pm 0.22 (\rm syst))\times 10^{-6} $ with a longitudinally polarization fraction $f_L = 0.21^{+0.18}_{-0.22} (\rm stat) \pm 0.11 (\rm syst)$. The branching fraction's upper limit is ${\cal B}(B^0 -> rho^0 rho^0) < 1.5 \times 10^{-6}$ at 90% confidence level. We use the longitudinal polarization fraction to determine the Cabibbo-Kobayashi-Maskawa matrix angle $\phi_2 = (91.0 \pm 7.2)^{\circ}$ through an isospin analysis in the $B\to\rho\rho$ system. We furthermore obtain ${\cal B}(B^0 -> rho^0 f_0) \times {\cal B}(f_0 -> \pi^+\pi^-) = (0.86 \pm 0.27 (\rm stat) \pm 0.15 (\rm syst))\times 10^{-6}$, corresponding to $149 \pm 49$ $B^0 -> rho^0 f_0$ events with a significance of 3.0 standard deviations and upper limits at 90% confidence level on the (product) branching fractions for possible decays with the same final state, ${\cal B}(B^0 -> pi^+\pi^-pi^+\pi^-) < 11.7 \times 10^{-6} $, ${\cal B}(B^0 -> rho^0 pi^+\pi^-) < 12.2 \times 10^{-6}$, ${\cal B}(B^0 -> f_0 pi^+\pi^-) \times {\cal B}(f_0->\pi^+\pi^-) < 3.1 \times 10^{-6}$ and ${\cal B}(B^0 -> f_0 f_0) \times {\cal B}(f_0->\pi^+\pi^-)^{2} < 0.2 \times 10^{-6}$.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: Observation of \psi(4040) and \psi(4160) decay into \eta J/\psi
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ABSTRACT: The cross section for e^+e^- \to \eta J/\psi between \sqrt{s}=3.8 GeV/c^2 and 5.3 GeV/c^2 is measured via initial state radiation using 980 fb^{-1} of data on and around the \Upsilon(nS)(n=1,2,3,4,5) resonances collected with the Belle detector at KEKB. Two resonant structures at the \psi(4040) and \psi(4160) are observed in the \eta J/\psi invariant mass distribution. Fitting the mass spectrum with the coherent sum of two Breit-Wigner functions, one obtains BR(\psi(4040)\to\eta J/\psi)\cdot\Gamma_{ee}^{\psi(4040)} = (4.8\pm0.9\pm1.4) eV and BR(\psi(4160)\to\eta J/\psi)\cdot\Gamma_{ee}^{\psi(4160)} = (4.0\pm0.8\pm1.4) eV for one solution and BR(\psi(4040)\to\eta J/\psi)\cdot\Gamma_{ee}^{\psi(4040)} = (11.2\pm1.3\pm1.9) eV and BR(\psi(4160)\to\eta J/\psi)\cdot\Gamma_{ee}^{\psi(4160)} = (13.8\pm1.3\pm2.0) eV for the other solution, where the first errors are statistical and the second are systematic. This is the first measurement of this hadronic transition mode of these two states, and the partial widths to \eta J/\psi are found to be about 1 MeV. There is no evidence for the Y(4260), Y(4360), \psi(4415), or Y(4660) in the \eta J/\psi final state, and upper limits of their production rates in e^+e^- annihilation are determined.10/2012; -
Article: Study of the Hadronic Transitions $\Upsilon$(2S)$\rightarrow (\eta,\pi^0)\Upsilon$(1S) at Belle
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ABSTRACT: We study the rare hadronic transitions $\Upsilon(2S)\rightarrow \Upsilon(1S)\eta$ and $\Upsilon(2S)\rightarrow \Upsilon(1S)\pi^0$ using a sample of 158 $\times 10^6$ $\Upsilon(2S)$ decays collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We observe the $\eta$ meson decay to $\gamma\gamma$ and $\pi^+\pi^-\pi^0$ final states; the $\Upsilon(1S)$ is reconstructed in the $\mu^+\mu^-$ and $e^+e^-$ decay modes. We measure the ratios of branching fractions (${\mathcal B}$) $\frac{{\mathcal B}(\Upsilon(2S)\rightarrow\Upsilon(1S)\eta)}{{\mathcal B}(\Upsilon(2S)\rightarrow\Upsilon(1S)\pi^+\pi^-)}$ = (1.99$\pm$0.14 (stat) $\pm$0.11 (syst)) $\times 10^{-3}$ and $\frac{{\mathcal B}(\Upsilon(2S)\rightarrow\Upsilon(1S)\pi^0)}{{\mathcal B}(\Upsilon(2S)\rightarrow\Upsilon(1S)\pi^+\pi^-)} < 2.3 \times 10^{-4}$ at the 90% confidence level (CL). Assuming the value ${\mathcal B}(\Upsilon(2S) \rightarrow \Upsilon(1S)\pi^-\pi^+)$ = (17.92$\pm$0.26)%, we obtain $ {\mathcal B}(\Upsilon(2S)\rightarrow\Upsilon(1S)\eta) = (3.57 \pm 0.25 ({\rm stat})\ \pm 0.21 ({\rm syst}))\times 10^{-4} $ and $ {\mathcal B}(\Upsilon(2S)\rightarrow\Upsilon(1S)\pi^0) < 4.1\times 10^{-5}\ ({\rm 90%\ CL}). $10/2012; -
Article: Measurements of Branching Fractions and Direct CP Asymmetries for B -> K pi, B->pi pi and B->to KK Decays
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ABSTRACT: We report measurements of the branching fractions and direct CP asymmetries (A_{CP}) for B->K pi, pi pi and KK decays (but not pi^0 pi^0) based on the final data sample of 772x10^6 B B-bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider. We set a 90% confidence-level upper limit for K^+- K^-+ at 2.0x10^{-7}; all other decays are observed with branching fractions ranging from 10^{-6} to 10^{-5}. In the $B^0/B^0-bar -> K^+-\pi^-+ mode, we confirm Belle's previously reported large A_{CP} with a value of -0.069 +- 0.014 +- 0.007 and a significance of 4.4 sigma. For all other flavor-specific modes, we find A_{CP} values consistent with zero, including A_{CP}(K^+- \pi^0) = +0.043 +- 0.024 +- 0.007 with 1.8 sigma significance. The difference of CP asymmetry between B^+- -> K^+- pi^0 and B^0/B^0-bar -> K^+-\pi^-+ is found to be Delta A_{K pi} equiv A_{CP} (K^+ pi^0) - A_{CP}(K^+ pi^-) = +0.112 +- 0.027 +- 0.007 with 4.0 sigma significance. We also calculate the ratios of partial widths for the B-> K pi decays. Using our results, we test the validity of the sum rule A_{CP}(K^+ pi^-) + A_{CP}(K^0\pi^+) x Gamma(K^0\pi^+)/Gamma(K^+ pi^-)} - A_{CP}(K^+ pi^0)x 2Gamma(K^+ pi^0)/Gamma(K^+ pi^-) - A_{CP}(K^0 pi^0)x 2Gamma(K^0 pi^0)/Gamma(K^+ pi^-) = 0 and obtain a sum of -0.270 +- 0.132 +- 0.060 with 1.9 sigma significance.10/2012; -
Article: Study of Three-Body Y(10860) Decays
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ABSTRACT: We report preliminary results on the analysis of the three-body Y(10860)=> B barB pi, Y(10860) => (B barB* + c.c.) pi and Y(10860)=> B* barB* pi decays including an observation of the Y(10860)=> Zb(10610)+- pi-+ => [B barB*+c.c]+- pi-+ and Y(10860)=> Zb(10650)+- pi-+ => [B* barB*]+- pi-+ decays as intermediate channels. We measure branching fractions of the three-body decays to be Br(Y(10860)=> [B barB*+c.c.]+- pi-+)=(28.3+-2.9+-4.6)x10^{-3} and Br(Y(10860)=> [B* barB*]+- pi-+)=(14.1+-1.9+-2.4)x10^{-3} and set 90% C.L. upper limit Br(Y(10860)=> [B barB]+- pi-+)<4.0x10^{-3}. We also report results on the amplitude analysis of the three-body Y(10860)=>Y(nS)pi+pi-, n=1,2,3 decays and the analysis of the internal structure of the three-body Y(10860)=>hb(mP)pi+pi-, m=1,2 decays. The results are based on a 121.4 1/fb data sample collected with the Belle detector at a center-of-mass energy near the Y(10860).09/2012; -
Article: Evidence for B- -> tau- nu_tau-bar with a Hadronic Tagging Method Using the Full Data Sample of Belle
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ABSTRACT: We measure the branching fraction of B- -> tau- nu_tau-bar using the full Upsilon(4S) data sample containing 772*10^6 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. Events with BBbar pairs are tagged by reconstructing one of the B mesons decaying into hadronic final states, and B- -> tau- nu_tau-bar candidates are detected in the recoil. We find evidence for B- -> tau- nu_tau-bar with a significance of 3.0 standard deviations including systematic errors and measure a branching fraction B(B- -> tau- nu_tau-bar) = [0.72^{+0.27}_{-0.25}(stat) +/- 0.11(syst)] * 10^-4.08/2012; -
Article: Precise measurement of the branching fractions for Bs->Ds(*)+ Ds(*)- and first measurement of the Ds*+ Ds*- polarization using e+e- collisions
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ABSTRACT: We have made a precise measurement of the absolute branching fractions of Bs->Ds(*)+ Ds(*)- decays using 121.4 fb-1 of data recorded by the Belle experiment running on the Upsilon(5S) resonance. The results are B(Bs0->Ds+ Ds-) = (0.58 +0.11 -0.09 +-0.13)%, B(Bs0->Ds*+- Ds-+) = (1.8 +-0.2 +-0.4)%, and B(Bs0->Ds*+ Ds*-) = (2.0 +-0.3 +-0.5)%; the sum is B(Bs0->Ds(*)+ Ds(*)- = (4.3 +-0.4 +-1.0)%. Assuming Bs->Ds(*)+ Ds(*)- saturates decays to CP-even final states, the branching fraction constrains the ratio Delta(Gamma_s)/cos(phi_s), where Delta(Gamma_s) is the difference in widths between the two Bs0-Bs0bar mass eigenstates, and phi_s is the CP-violating phase in Bs0-Bs0bar mixing. For phi_s=0 we obtain Delta(Gamma_s)/Gamma_s = 0.090 +-0.009 (stat.) +-0.023 (syst.), where Gamma_s is the mean decay width. We also measure for the first time the longitudinal polarization fraction of Bs->Ds*+ Ds*-; the result is 0.12 +0.30 -0.28 +0.04 -0.05.08/2012; -
Article: Evidence for B- -> Ds+ K- l- nubar and search for B- -> Ds*+ K- l- nubar
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ABSTRACT: We report measurements of the decays B- -> Ds(*)+ K- l- nubar in a data sample containing 657x10^6 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We observe a signal with a significance of 6 sigma for the combined Ds and Ds* modes and find the first evidence of the B- -> Ds+ K- l- nubar decay with a significance of 3.4 sigma. We measure the following branching fractions: BF(B- -> Ds+ K- l nubar) = (0.30 +/- 0.09(stat) +0.11 -0.08(syst)) x 10^-3 and BF(B- -> Ds*+ K- l- nubar) = (0.59 +/- 0.12(stat) +/- 0.15(syst)) x 10^-3 and set an upper limit BF(B- -> Ds*+ K- l- nubar) < 0.56 x 10^-3 at the 90% confidence level. We also present the first measurement of the Ds+K- invariant mass distribution in these decays, which is dominated by a prominent peak around 2.6 GeV/c^2.07/2012; -
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;
Top co-authors
Top Journals
Institutions
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2012
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National Taiwan University
- Department of Physics
Taipei, Taipei, Taiwan -
Novosibirsk State University
Novosibirsk, Novosibirskaya Oblast', Russia
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2011–2012
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Tohoku University
- Research Center for Electron Photon Science
Sendai, Kagoshima-ken, Japan -
University of Illinois, Urbana-Champaign
Urbana, IL, USA -
Seoul National University
Seoul, Seoul, South Korea -
Panjab University
Chandīgarh, Union Territory of Chandigarh, India
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2010–2012
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High Energy Accelerator Research Organization
Tsukuba, Ibaraki-ken, Japan -
Institute for Theoretical and Experimental Physics
Moscow, Moscow, Russia -
Korea University
Seoul, Seoul, South Korea -
Honolulu University
Honolulu, HI, USA -
Chinese Academy of Sciences
- Institute of High Energy Physics (IHEP)
Beijing, Beijing Shi, China -
University of Cincinnati
Cincinnati, OH, USA
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