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 Physics , 2013, DOI: 10.1103/PhysRevLett.112.031801 Abstract: The lifetime of the $\tau$-lepton is measured using the process $e^+e^-\rightarrow\tau^+\tau^-$, where both $\tau$-leptons decay to $3\pi\nu_\tau$. The result for the mean lifetime, based on $711\,\mathrm{fb}^{-1}$ of data collected with the Belle detector at the $\Upsilon(4S)$ resonance and $60\,\mathrm{MeV}$ below, is $\tau = (290.17 \pm 0.53(\mathrm{stat.}) \pm 0.33(\mathrm{syst.}))\cdot10^{-15}\,\mathrm{s}$. The first measurement of the lifetime difference between $\tau^+$ and $\tau^-$ is performed. The upper limit on the relative lifetime difference between positive and negative $\tau$-leptons is $|\Delta\tau| / \tau < 7.0 \times 10^{-3}$ at 90% CL.
 William Trischuk Physics , 2002, Abstract: The Belle experiment at the KEK $B$ factory has collected 93 fb$^{-1}$ of electron positron collisions at $\sqrt s = 10.6$ GeV. This has produced a sample of 85 million $B {\bar B}$ meson pairs that can be used to study $CP$ violation in rare (and not so rare) B decay modes. Here I report on a measurement of indirect CP violation in the decay $B^0 \to J/\psi K^0_S$, as well as time dependent CP asymmetries in rarer modes such as $B^0 \to \pi^+ \pi^-, \eta' K_S^0$ and $\phi K^0_S$. I summarise the prospects for improving the precision on these and related measurements.
 Physics , 2004, DOI: 10.1016/j.nima.2004.06.159 Abstract: We describe a flavor tagging algorithm used in measurements of the CP violation parameter sin2phi_1 at the Belle experiment. Efficiencies and wrong tag fractions are evaluated using flavor-specific B meson decays into hadronic and semileptonic modes. We achieve a total effective efficiency of $28.8 +- 0.6 %.  Jun-ichi Tanaka Physics , 2000, DOI: 10.1142/S0217751X01007406 Abstract: The lifetimes of charmed mesons have been measured using 2.75fb$^{-1}$of data collected with the Belle detector at KEKB. Each candidate is fully reconstructed to identify the flavor of the charmed meson. The lifetimes are measured to be$\tau(D^0)=(414.8\pm3.8\pm3.4)$fs,$\tau(D^+)=(1040^{+23}_{-22}\pm18)$fs and$\tau(D_s^+)=(479^{+17}_{-16}{}^{+6}_{-8})$fs, where the first error is statistical and the second error is systematic. The mixing parameter$y_{CP}$is also measured through the lifetime difference of$D^0$mesons decaying into CP-mixed states and CP eigenstates. We find$y_{CP}=(1.0^{+3.8}_{-3.5}{}^{+1.1}_{-2.1})%$, corresponding to a 95% confidence interval$-7.0%<\ycp<8.7%$.  Uehara Sadaharu EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20123705009 Abstract: We report a measurement of the process γγ* → π0 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(Q2), is measured for the kinematical region GeV2 Q2 40 GeV2, where Q2 is the invariant mass squared of a virtual photon. The measured values of Q2|F(Q2)| agree well with the previous measurements below Q2 9 GeV2 but do not exhibit the rapid growth in the higher Q2 region seen in another recent measurement, which exceeds the asymptotic QCD expectation by as much as 50%.  Statistics , 2002, DOI: 10.1103/PhysRevD.66.071102 Abstract: We present an improved measurement of the standard model CP violation parameter sin2phi_1 (also known as sin2beta) based on a sample of 85 times 10^6 B Bbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is reconstructed in a J/psi K_S, psi(2S) K_S, chi_{c1} K_S, eta_c K_S, J/psi K^{*0}, or J/psi K_L CP-eigenstate decay channel and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time interval between the two B meson decay points, we obtain sin2phi_1 = 0.719 +/- 0.074(stat) +/- 0.035(syst).  Statistics , 2002, Abstract: We present an improved measurement of the standard model CP violation parameter sin2phi_1 (also known as sin2beta) based on a sample of 85 times 10^6 B Bbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is reconstructed in a J/psi K_S, psi(2S) K_S, chi_{c1} K_S, eta_c K_S, J/psi K^{*0}, or J/psi K_L CP-eigenstate decay channel and the flavor of accompanying B meson is identified from itsdecay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we obtain sin2phi_1 = 0.719 +/- 0.074(stat) +/- 0.035(syst). We also report measurements of CP violation parameters for the related B^0 -> J/psi pi^0 decay mode and the penguin-dominated processes B^0 -> eta' K_S, phi K_S and K^+K^- K_S.  Physics , 2009, Abstract: A first measurement of the di-hadron interference fragmentation function of light quarks in pion pairs with the Belle detector is presented. The chiral odd nature of this fragmentation function allows the use as a quark polarimeter sensitive to the transverse polarization of the fragmenting quark. Therefore it can be used together with data taken at fixed target and collider experiments to extract the quark transversity distribution. A sample consisting of$711 \times 10^6$di-hadron pairs was extracted from 661$fb^{-1}$of data recorded near the$\Upsilon(4S)$resonance delivered by the KEKB$e^+e^{-}\$ collider.