M. Bischofberger

Publications (123)174.88 Total impact

• Article: Measurement of exclusive $\Upsilon(1S)$ and $\Upsilon(2S)$ decays into Vector-Pseudoscalar final states

  Belle Collaboration, C. P. Shen, C. Z. Yuan, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, A. M. Bakich, A. Bala, B. Bhuyan, [......], E. Won, H. Yamamoto, J. Yamaoka, Y. Yamashita, S. Yashchenko, Y. Yook, Y. Yusa, C. C. Zhang, Z. P. Zhang, A. Zupanc
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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 $\ks K^+ \pi^-$ and charge-conjugate (c.c.) states, $\pi^+ \pi^- \pi^0 \pi^0$, and $\pi^+ \pi^- \pi^0$, and to the two-body Vector-Pseudoscalar ($K^{\ast}(892)^0\bar{K}^0+ {\rm c.c.}$, $K^{\ast}(892)^-K^+ + {\rm c.c.}$, $\omega\pi^0$, and $\rho\pi$) final states. For the first time, signals are observed in the modes $\Upsilon(1S) \to \ks K^+ \pi^- + {\rm c.c.}$, $\pi^+ \pi^- \pi^0 \pi^0$, and $\Upsilon(2S) \to \pi^+ \pi^- \pi^0 \pi^0$, and evidence is found for the modes $\Upsilon(1S)\to \pi^+ \pi^- \pi^0$, $K^{\ast}(892)^0 \bar{K}^0+ {\rm c.c.}$, and $\Upsilon(2S) \to \ks K^+ \pi^- + {\rm c.c.}$ Branching fractions are measured for all the processes, while 90% confidence level upper limits on the branching fractions are also set for the modes with a statistical significance of 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.
  05/2013;
• Article: Evidence for B_s^0 -> Lambda_c^+ Lambda-bar pi^-

  Belle Collaboration, E. Solovieva, R. Chistov, I. Adachi, D. M. Asner, T. Aushev, A. M. Bakich, A. Bala, V. Bhardwaj, B. Bhuyan, [......], Y. Watanabe, K. M. Williams, E. Won, B. D. Yabsley, Y. Yamashita, S. Yashchenko, Y. Yook, Z. P. Zhang, V. Zhilich, A. Zupanc
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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 $B \to \chi_{c1} \gamma K$

  Belle Collaboration, V. Bhardwaj, K. Miyabayashi, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, T. Aziz, A. M. Bakich, [......], J. Yamaoka, Y. Yamashita, S. Yashchenko, Y. Yook, C. Z. Yuan, C. C. Zhang, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc
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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

  Belle Collaboration, Z. Q. Liu, C. P. Shen, C. Z. Yuan, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, T. Aziz, [......], B. D. Yabsley, J. Yamaoka, Y. Yamashita, S. Yashchenko, Y. Yook, Y. Yusa, C. C. Zhang, Z. P. Zhang, V. Zhilich, A. Zupanc
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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: Measurement of the CP Violation Parameters in B0 -> pi+ pi- Decays

  Belle Collaboration, I. Adachi, K. Adamczyk, H. Aihara, K. Arinstein, Y. Arita, D. M. Asner, T. Aso, V. Aulchenko, T. Aushev, [......], L. M. Zhang, Z. P. Zhang, L. Zhao, V. Zhilich, P. Zhou, V. Zhulanov, T. Zivko, A. Zupanc, N. Zwahlen, O. Zyukova
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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: Study of B^0 -> rho^0 rho^0 decays, implications for the CKM angle phi_2 and search for other four pion final states

  I. Adachi, K. Adamczyk, H. Aihara, K. Arinstein, Y. Arita, D. M. Asner, T. Aso, V. Aulchenko, T. Aushev, T. Aziz, [......], L. M. Zhang, Z. P. Zhang, L. Zhao, V. Zhilich, P. Zhou, V. Zhulanov, T. Zivko, A. Zupanc, N. Zwahlen, O. Zyukova
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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

  R Mizuk, D M Asner, A Bondar, T K Pedlar, I Adachi, H Aihara, K Arinstein, V Aulchenko, T Aushev, T Aziz, [......], M Watanabe, Y Watanabe, K M Williams, E Won, B D Yabsley, J Yamaoka, Y Yamashita, C Z Yuan, Z P Zhang, V Zhilich
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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: Measurements of Branching Fractions and Direct CP Asymmetries for B -> K pi, B->pi pi and B->to KK Decays

  Y. -T. Duh, T. -Y. Wu, P. Chang, G. B. Mohanty, Y. Unno, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, [......], M. -Z. Wang, M. Watanabe, K. M. Williams, E. Won, B. D. Yabsley, Y. Yamashita, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc
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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

  I. Adachi, K. Adamczyk, H. Aihara, K. Arinstein, Y. Arita, D. M. Asner, T. Aso, V. Aulchenko, T. Aushev, T. Aziz, [......], L. M. Zhang, Z. P. Zhang, L. Zhao, V. Zhilich, P. Zhou, V. Zhulanov, T. Zivko, A. Zupanc, N. Zwahlen, O. Zyukova
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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- -> Ds+ K- l- nubar and search for B- -> Ds*+ K- l- nubar

  Belle Collaboration, J. Stypula, M. Rozanska, I. Adachi, K. Adamczyk, H. Aihara, D. M. Asner, T. Aushev, A. M. Bakich, V. Bhardwaj, [......], J. Wiechczynski, K. M. Williams, E. Won, B. D. Yabsley, H. Yamamoto, Y. Yamashita, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc
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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: Evidence for a Zb0(10610) in Dalitz analysis of Y(5S) -> Y(nS) pi0 pi0

  I. Adachi, K. Adamczyk, H. Aihara, K. Arinstein, Y. Arita, D. M. Asner, T. Aso, V. Aulchenko, T. Aushev, T. Aziz, [......], L. M. Zhang, Z. P. Zhang, L. Zhao, V. Zhilich, P. Zhou, V. Zhulanov, T. Zivko, A. Zupanc, N. Zwahlen, O. Zyukova
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  ABSTRACT: We report the first observation of Y(5S) -> Y(1,2S) pi0 pi0 decays. Evidence for the Zb0(10610) with 4.9sigma significance is found in a Dalitz plot analysis of Y(5S) -> Y(2S) pi0 pi0 decays. The results are obtained with a 121.4 fb^-1 data sample collected with the Belle detector at the Y(5S) resonance at the KEKB asymmetric-energy e+e- collider.
  07/2012;
• Article: Evidence for CP Violation in the Decay D^{+}→K_{S}^{0}π^{+}.

  B R Ko, E Won, I Adachi, H Aihara, D M Asner, V Aulchenko, T Aushev, T Aziz, A M Bakich, K Belous, [......], M Watanabe, Y Watanabe, H Yamamoto, Y Yamashita, C Z Yuan, C C Zhang, Z P Zhang, V Zhilich, V Zhulanov, A Zupanc
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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

  Belle Collaboration, C. -L. Hsu, P. Chang, I. Adachi, H. Aihara, K. Arinstein, D. M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, [......], P. Wang, M. Watanabe, Y. Watanabe, K. M. Williams, E. Won, H. Yamamoto, Y. Yamashita, Z. P. Zhang, V. Zhilich, V. Zhulanov
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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

  H. Aihara, K. Arinstein, D. M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, K. Belous, B. Bhuyan, M. Bischofberger, A. Bondar, [......], E. Won, B. D. Yabsley, H. Yamamoto, J. Yamaoka, Y. Yamashita, C. Z. Yuan, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc
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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

  Y. Miyazaki, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, A. Bay, V. Bhardwaj, B. Bhuyan, [......], S. Uno, P. Urquijo, G. Varner, C. H. Wang, P. Wang, E. Won, Y. Yamashita, Y. Yusa, Z. P. Zhang, V. Zhulanov
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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

  Belle Collaboration, C. C. Zhang, H. Aihara, D. M. Asner, T. Aushev, A. M. Bakich, Y. Ban, K. Belous, M. Bischofberger, T. E. Browder, [......], V. Vorobyev, P. Wang, X. L. Wang, Y. Watanabe, K. M. Williams, B. D. Yabsley, Y. Yamashita, C. Z. Yuan, Z. P. Zhang, V. Zhulanov
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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

  Belle collaboration, J. H. Kim, M. Nakao, I. Adachi, K. Adamczyk, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, [......], M. Watanabe, Y. Watanabe, K. M. Williams, E. Won, H. Yamamoto, Y. Yamashita, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc
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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

  Belle Collaboration, R. Mizuk, D. M. Asner, A. Bondar, T. K. Pedlar, I. Adachi, H. Aihara, K. Arinstein, V. Aulchenko, T. Aushev, [......], M. Watanabe, Y. Watanabe, K. M. Williams, E. Won, B. D. Yabsley, J. Yamaoka, Y. Yamashita, C. Z. Yuan, Z. P. Zhang, V. Zhilich
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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: Measurements of branching fractions and time-dependent CP violating asymmetries in B0 → D(*)± D∓ decays

  M. Rohrken, I. Adachi, H. Aihara, David M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, Matthew Barrett, K. Belous, V. Bhardwaj, [......], Y. Watanabe, K. M. Williams, E. Won, H. Yamamoto, Y. Yamashita, D. Zander, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc
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  ABSTRACT: We report measurements of branching fractions and time-dependent CP asymmetries in B{sup 0} {yields} D{sup +}D{sup -} and B{sup 0} {yields} D*{sup {+-}}D{sup {-+}} decays using a data sample that contains (772 {+-} 11) x 10{sup 6} BB{sup -} pairs collected at the {Upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. We determine the branching fractions to be {Beta}(B{sup 0} {yields} D{sup +}D{sup -}) = (2.12 {+-} 0.16 {+-} 0.18) x 10{sup -4} and {Beta}(B{sup 0} {yields} D*{sup {+-}}D{sup {-+}}) = (6.14 {+-} 0.29 {+-} 0.50) x 10{sup -4}. We measure CP asymmetry parameters S{sub D{sup +}D{sup -}} = -1.06{sub -0.14}{sup +0.21} {+-} 0.08 and C{sub D{sup +}D{sup -}} = -0.43 {+-} 0.16 {+-} 0.05 in B{sup 0} {yields} D{sup +}D{sup -} and A{sub D*D} = +0.06 {+-} 0.05 {+-} 0.02, S{sub D*D} = -0.78 {+-} 0.15 {+-} 0.05, C{sub D*D} = -0.01 {+-} 0.11 {+-} 0.04, {Delta}S{sub D*D} = -0.13 {+-} 0.15 {+-} 0.04 and {Delta}C{sub D*D} = +0.12 {+-} 0.11 {+-} 0.03 in B{sup 0} {yields} D*{sup {+-}}D{sup {-+}}, where the first uncertainty is statistical and the second is systematic. We exclude the conservation of CP symmetry in both decays at equal to or greater than 4{sigma} significance.
  Physical Review. D, Particles, Fields, Gravitation and Cosmology. 05/2012; 85(9).
• Article: Measurement of gamma gamma* --> pi0 transition form factor at Belle

  The Belle Collaboration, S. Uehara, Y. Watanabe, H. Nakazawa, I. Adachi, H. Aihara, D. M. Asner, T. Aushev, A. M. Bakich, K. Belous, [......], M. Watanabe, K. M. Williams, E. Won, Y. Yamashita, C. Z. Yuan, C. C. Zhang, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc
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  ABSTRACT: We report a measurement of the process gamma gamma* --> pi0 with a 759 fb^{-1} data sample recorded with the Belle detector at the KEKB asymmetric-energy e+e- collider. The pion transition form factor, F(Q^2), is measured for the kinematical region 4 GeV^2 <~ Q^2 <~ 40 GeV^2, where -Q^2 is the invariant mass squared of a virtual photon. The measured values of Q^2|F(Q^2)| agree well with the previous measurements below Q^2 ~= 9 GeV^2 but do not exhibit the rapid growth in the higher Q^2 region seen in another recent measurement, which exceeds the asymptotic QCD expectation by as much as 50%.
  05/2012;