arXiv subjects

The Belle collaboration

Publications and source records attributed to The Belle collaboration.

3 recordsLinked to original sources

arXiv2010

Evidence for B- -> tau- nu_bar with a Semileptonic Tagging Method

We present a measurement of the decay B- -> tau- nu_bar using a data sample containing 657 million BB_bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. A sample of BB_bar pairs are tagged by reconstructing one B meson decaying semileptonically. We detect the B- -> tau- nu_bar candidate in the recoil. We obtain a signal with a significance of 3.6 standard deviations including systematic uncertainties, and measure the branching fraction to be Br(B- -> tau- nu_bar) = [1.54+0.38-0.37(stat)+0.29-0.31(syst)]*10^-4. This result confirms the evidence for B- -> tau- nu_bar obtained in a previous Belle measurement that used a hadronic B tagging method.

hep-ex↗

arXiv2007

Measurement of the absolute branching fraction of the Ds+- meson

The Ds+- -> K+-K-+pi+- absolute branching fraction is measured using e+e- -> Ds*+- Ds1-+(2536) events collected by the Belle detector at the KEKB e+e- asymmetric energy collider. Using the ratio of yields when either the Ds1 or Ds* is fully reconstructed, we find Br(Ds+- -> K+-K-+pi+-)= (4.0+-0.4(stat)+-0.4(sys))%.

hep-ex↗

arXiv2002

Measurement of the inclusive semileptonic branching fraction of B mesons and |Vcb|

We present a measurement of the electron spectrum from inclusive semileptonic {\it B} decay, using 5.1 fb$^{-1}$ of $Υ(4S)$ data collected with the Belle detector. A high-momentum lepton tag was used to separate the semileptonic {\it B} decay electrons from secondary decay electrons. We obtained the branching fraction, ${\cal B}(B\to X e^+ ν) = (10.90 \pm 0.12 \pm 0.49)%$, with minimal model dependence. From this measurement, we derive a value for the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}| = 0.0408 \pm 0.0010 {\rm (exp)} \pm 0.0025{\rm (th)}$.

hep-ex↗