Results for " Belle Collaboration"
total 15638took 0.10s
Search for the Electric Dipole Moment of the tau leptonOct 15 2002We have searched for a T/CP violation signature arising from an electric dipole form factor (d_tau) of the tau lepton in the e+e- -> tau+tau- reaction. Using an optimal observable method for 29.5 fb^{-1} of data collected with the Belle detector at the ... More Measurement of the e+e- --> D(*)+D(*)- cross-sectionsJul 30 2003Nov 27 2003In this paper we report the first measurement of $e^+e^- \to D^{(*)+}D^{(*)-}$ processes. The cross-sections for $e^+^e- \to D^{*+}D^{*-}$ and $e^+e^- \to D^+D^{*-}$ at $\sqrt{s}=10.58\mathrm{GeV}/c^2$ have been measured to be $0.65 \pm 0.04 \pm 0.07 ... More Measurement of χ_{c2} Production in Two-Photon CollisionsMay 30 2002The production of the \chi_{c2} charmonium state in two-photon collisions has been measured with the Belle detector at the KEKB e^+e^- collider. A clear signal for \chi_{c2} --> \gamma J/\psi, J/\psi --> l^+l^- is observed in a 32.6fb^{-1} data sample ... More A High Statistics Study of the Decay tau- -> pi- pi0 nuDec 28 2005We report a measurement of the branching fraction for tau- -> pi- pi0 nu and the invariant mass spectrum of the resulting pi- pi0 system using 72.2 /fb of data recorded by the Belle detector at the KEKB e+e- collider. The branching fraction obtained is ... More Observation of Large CP Violation in the Neutral B Meson SystemJul 23 2001Aug 01 2001We present a measurement of the Standard Model CP violation parameter sin 2phi_1 based on a 29.1 fb^{-1} data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is fully ... More Study of charmless B decays to three-kaon final statesAug 19 2002We report on a study of charmless B meson decays to three-kaon final states. The results are obtained with a 78.7 1/fb data sample collected on the Y(4S) resonance by the Belle detector operating at the KEKB asymmetric energy $e^+e^-$ collider. The branching ... More Measurement of the ratio Br(D0 --> pi+pi-pi0)/Br(D0 --> K-pi+pi0)Oct 20 2006Oct 24 2006We report a high-statistics measurement of the relative branching fraction Br(D0 --> pi+pi-pi0)/Br(D0 --> K-pi+pi0). A 357 inverse fb data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider was used for the analysis. ... More Measurement of phi1 using B --> D[Ks pi+ pi-] h0Jul 14 2005We present a preliminary measurement of the angle phi1 of the CKM Unitarity Triangle using time-dependent analysis of D -> Ks pi+ pi- decays produced in neutral B meson decay to a neutral D meson and a light meson (B -> D h). The method allows one to ... More Study of B0 -> \bar{D}(*)0 pi+ pi- decaysDec 28 2004We report the results of a study of neutral B decays to the $D^0 \pi^+ \pi^-$ and $D^{*0} \pi^+ \pi^-$ final states using complete $D^{(*)0}$ reconstruction. The contributions from two-body $B\to D^{**} \pi$ with narrow ($j_q=3/2$) $D^{**}$ states and ... More Study of B+- --> D_CP K+- and D^*_CP K+- decaysJan 18 2006Feb 20 2006We report a study of the modes D_CP K+- and D^*_CP K+- where D^(*) decays to CP eigenstates. The data sample used contains 275 x 10^6 BB events at the Upsilon(4S) resonance collected by the Belle detector at the KEKB energy-asymmetric e^+ e^- collider. ... More Improved Measurements of B0bar -> DsJ+ K- decaysJul 14 2005We report an improved measurement of the branching fraction for B0bar -> DsJ*(2317)+ K- and present evidence of the B0bar -> DsJ(2460)+ K- decay. These results are obtained from a data sample containing 386 million BBbar pairs that was collected near ... More CP violation in B-$\bar{B}$ mixing with dilepton eventsSep 02 2004We report a measurement of the charge asymmetry for same-sign dileptons in $B^0$-$\bar B^0$ mixing. The data were collected with the Belle detector at KEKB. Using a data sample of 78 fb^{-1} recorded at the $\Upsilon(4S)$ resonance and 9 fb^{-1} recorded ... More Search for the b --> d gamma processAug 27 2004We report search results for the flavor-changing neutral current process b --> d gamma with a data sample containing 274 million B meson pairs accumulated at the Upsilon(4S) resonance with the Belle detector at KEKB. We studied the exclusive decays B- ... More Study of X(3872) in $B$ meson decaysSep 07 2008We present results on the X(3872), produced in $B^+ \to X(3872) K^+$ and $B^0 \to X(3872) K^0_S$ decays where $X(3872) \to J/\psi \pi^+ \pi^-$. We report the first statistically significant observation of $B^0 \to X(3872) K^0_S$ and measure the ratio ... More Observation of h_b(1P)->eta_b(1S)gammaOct 18 2011We report the first observation of the radiative transition h_b(1P)->eta_b(1S)gamma, where the h_b(1P) is produced in Upsilon(5S)->h_b(1P)pi+pi- dipion transitions. We measure the eta_b(1S) mass to be (9401.0+-1.9+1.4-2.4)MeV/c^2 with a width of (12.4+5.5-4.6+11.5-3.4)MeV ... More Measurement of B(Ds -> munu)Sep 10 2007Feb 21 2008We present a measurement of the branching fraction $B(D_s^+\to\mu^+\nu_\mu)$ using a 548 fb$^{-1}$ data sample collected by the Belle experiment at the KEKB $e^+e^-$ collider. The $D_s$ momentum is determined by reconstruction of the system recoiling ... More Search for the Electric Dipole Moment of the tau LeptonOct 31 2002Nov 15 2002We have searched for a CP violation signature arising from an electric dipole moment (d_tau) of the tau lepton in the e+e- -> tau+tau- reaction. Using an optimal observable method and 29.5 fb^{-1} of data collected with the Belle detector at the KEKB ... More Study of Michel parameters in leptonic $τ$ decays at BelleSep 17 2014We present a study of Michel parameters in leptonic $\tau$ decays using experimental information collected at the Belle detector. Michel parameters are extracted in the unbinned maximum likelihood fit of the $(\tau^\mp\to\ell^\mp\nu\nu,\tau^\pm\to\pi^\pm\pi^0\nu)$ ... More Comment on "e+ e- annhilation into J/psi J/psi"Jun 05 2003Using a data sample of 101.8 fb collected by the Belle detector at the KEKB asymmetric energy e+ e- collider, we confirm our published observation of e+ e- -> J/psi eta_c and find no evidence for the process e+ e- -> J/psi J/psi. The latter process was ... More B CP-Violation, Mixing and Lifetime Results from BelleMay 14 2001Recent results on the $B$ CP-violation parameter $\sin2\phi_1$, the $B^0_d$-$\overline{B}^0_d$ mixing parameter $\Delta m_d$ and $B$-meson lifetimes are reported. The results are based on 10.5 $fb^{-1}$ of data collected with the Belle detector at KEKB. ... More Study of B -> ρπdecays at BelleJul 01 2002This paper describes a study of B meson decays to the pseudoscalar-vector final state \rho\pi using 31.9\times 10^6 B\bar{B} events collected with the Belle detector at KEKB. The branching fractions B(B^+ \to \rho^0\pi^+) = (8.0^{+2.3+0.7}_{-2.0-0.7}) ... More Search for B0 -> rho0rho0 and Non-Resonant B0 -> 4pi DecaysAug 15 2007We search for the decay B0 -> rho0rho0 and other possible charmless modes with a pi+pi-pi+pi- final state, including B0 -> rho0f0(980), B0 -> f0(980)f0(980), B0 -> f0(980)pipi, B0 -> rho0pipi and non-resonant B0 -> 4pi. These results are obtained from ... More Observation of B->J/psi K1(1270)May 09 2001We report the first observation of the exclusive decay process B->J/psi K1(1270) using a sample of 11.2M BBbar meson pairs collected in the Belle detector at the KEKB asymmetric e+e- collider. We measure branching fractions of Bf(B0 -> J/psi K10(1270) ... More Search for Lepton-number-violating B+->D-l+l'+ DecaysJul 04 2011We perform the first search for lepton-number-violating B+->D-l+l'+ decays, where l and l' stand for e or mu, using 772 x 10^6 BB-bar pairs accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB e^+e^- collider. No evidence for these ... More Observation of B -> D^{(*)} K^- K^{0(*)} decaysJul 17 2002The B -> D^{(*)} K^- K^{(*)0} decays have been observed for the first time. The branching fractions of the B -> D^{(*)} K^- K^{(*)0} decay modes are measured. Significant signals are found for the B -> D^{(*)} K^- K^{*0} and B^- -> D^0 K^- K^0_S decay ... More Measurement of Br(Bbar -> D+l-nubar) and Determination of |Vcb|Nov 26 2001Dec 19 2001We present a measurement of the branching fraction for the semileptonic B decay Bbar -> D+l-nubar, where l- can be either an electron or a muon. We find Gamma(Bbar -> D+l-nubar)= (13.79+/-0.76+/-2.51) ns^{-1}, and the resulting branching fraction Br(Bbar ... More Observation of the decay B^0->D+D*-Jun 06 2002Oct 06 2002We report the first observation of the decay B^0->D+-D*-+ with the Belle detector at the KEKB e^+e^- collider operated at the Upsilon(4S) resonance. The sum of branching fractions B(B^0->D+D*-)+B(B^0->D-D*+) is measured to be (1.17+-0.26+0.22-0.25)x10^-3 ... More A Measurement of Lifetime Difference in $D^0$ Meson DecaysNov 08 2001Mar 15 2002We report a measurement of the $D^0$-$\bar{D}{}^0$ mixing parameter $y_{CP}$ using 23.4 fb$^{-1}$ of data collected near the $\Upsilon$(4S) resonance with the Belle detector at KEKB. $y_{CP}$ is measured from the lifetime difference of $D^0$ mesons decaying ... More Evidence for B to K eta' gamma Decays at BelleOct 05 2008Aug 07 2009We present the results of a search for the radiative decay (B -> K eta' gamma) and find evidence for (B^+ -> K^+ eta' gamma) decays at the 3.3 standard deviation level with a partial branching fraction of (3.6 +/- 1.2 +/- 0.4) x 10e-6, where the first ... More Search for the dark photon and the dark Higgs boson at BelleJan 31 2015Apr 29 2015The dark photon, $A^\prime$, and the dark Higgs boson, $h^\prime$, are hypothetical constituents featured in a number of recently proposed Dark Sector Models. Assuming prompt decays of both dark particles, we search for their production in the so-called ... More Improved search for D^0 mixing using semileptonic decays at BelleFeb 20 2008Apr 21 2008A search for mixing in the neutral D meson system has been performed using semileptonic D0 -> K(*)- e+ \nu and D0 -> K(*)- \mu+ \nu decays. Neutral D mesons from D*+ -> D0 \pi_s^+ decays are used and the flavor at production is tagged by the charge of ... More Observation of two charged bottomonium-like resonancesMay 23 2011Nov 24 2011We report the observation of two narrow structures at 10610MeV/c^2 and 10650MeV/c^2 in the pi^{\pm}Upsilon(nS) (n=1,2,3) and pi^{\pm}h_b(mP) (m=1,2) mass spectra that are produced in association with a single charged pion in Upsilon(5S) decays. The measured ... More Studies of CP violation in $B^0 \to J/ψK^{*0}$ decaysAug 23 2004Oct 18 2004An angular analysis for B decays into two vector mesons gives parameters sensitive to new physics. They are the decay amplitudes of the three helicity states, the asymmetry in triple product, and the CP violating phase. The measurements of these quantities ... More Observation of B+ -> chi_c0 K+Nov 22 2001Nov 23 2001Using a sample of $31.3 x 10^6 $B\bar{B}$ pairs collected with the Belle detector at the Y(4S) resonance, we make the first observation of the charged B meson decay to chi_c0 and a charged kaon. The measured branching fraction is Br(B+ -> chi_c0 K+)=(6.0^{+2.1}_{-1.8}\pm1.1)x10^{-4}, ... More Study of $\bar{B^0}\to {D}^0 π^+ π^-$ decaysNov 29 2006We report the results of a study of neutral B meson decays to the D^0 pi+ pi- final state, where the D^0 is fully reconstructed. The results are obtained from an event sample containing 388 million BB-bar -meson pairs collected in the Belle experiment ... More Observation of a new DsJ meson in B+ -> D0-bar D0 K+ decaysAug 10 2006We report the observation of a new DsJ meson produced in B+ -> D0-bar DsJ -> D0-bar D0 K+. This state has a mass of M = 2715 +-11(stat) +11-14(syst) MeV/c^2, a width Gamma = 115 +-20(stat) +36-32(syst) MeV/c^2 and a spin-parity 1-. The results are based ... More Study of three-body charmless B decays at BelleJul 20 2001Using a data sample of 21.3 fb$^{-1}$ collected by the Belle detector, three body charmless decays $B^+\to K^+ h^+ h^-$ have been studied. With no assumptions on the intermediate mechanisms, the following branching fractions have been measured for the ... More Search for \bar{B}^0\toΛ_c^+\barΛ_c^- decay at BelleAug 08 2007Oct 06 2007We search for the doubly charmed baryonic decay $\bar{B}^0\to\Lambda_c^+\bar{\Lambda}_c^-$, in a data sample of $520\times10^6$ $B{\bar B}$ events accumulated at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric e^+e^- collider. ... More Study of $B^0 \to ηK^+ π^-$ and $ηπ^+ π^-$Sep 02 2005We report results of studies of inclusive $B \to \eta K^+ \pi^-$ and $B \to \eta \pi^+ \pi^-$ decays. Charged conjugates are implied throughout this paper. These are obtained from a data sample containing 386 million $B\bar{B}$ pairs, collected at the ... More Measurement of masses of $Ξ_c(2645)$ and $Ξ_c(2815)$ baryonsAug 04 2006We report a precise measurement of masses of the $\Xi_c(2645)$ and $\Xi_c(2815)$ baryons using data collected by the Belle experiment at the KEKB $e^+ e^-$ collider. The states $\Xi_c(2645)^{0,+}$ are observed in the $\Xi_c^{+,0}\pi^{-,+}$ decay modes, ... More