Study of τ−→KSπ−ντ decay at Belle Epifanov, D.; Aihara, H.; Aulchenko, V. ...
Physics letters. B,
10/2007, Letnik:
654, Številka:
3-4
Journal Article
Recenzirano
We present a study of the decay τ−→KSπ−ντ using a 351 fb−1 data sample collected with the Belle detector. The analysis is based on 53,110 lepton-tagged signal events. The measured branching fraction ...B(τ−→KSπ−ντ)=(0.404±0.002(stat.)±0.013(syst.))% is consistent with the world average value and has better accuracy. An analysis of the KSπ− invariant mass spectrum reveals contributions from the K∗(892)− as well as other states. For the first time the K∗(892)− mass and width have been measured in τ decay: M(K∗(892)−)=(895.47±0.20(stat.)±0.44(syst.)±0.59(mod.)) MeV/c2, Γ(K∗(892)−)=(46.2±0.6(stat.)±1.0(syst.)±0.7(mod.)) MeV. The K∗(892)− mass is significantly different from the current world average value.
We report on a search for the lepton flavor violating τ−→μ−γ and τ−→e−γ decays based on 535 fb−1 of data accumulated at the Belle experiment. No signal is found and we set 90% confidence level upper ...limits on the branching ratios B(τ−→μ−γ)<4.5×10−8 and B(τ−→e−γ)<1.2×10−7.
We have studied hadronic τ decay modes involving an η meson using 490 fb−1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. The following branching fractions ...have been measured: B(τ−→K−ηντ)=(1.58±0.05±0.09)×10−4, B(τ−→K−π0ηντ)=(4.6±1.1±0.4)×10−5, B(τ−→π−π0ηντ)=(1.35±0.03±0.07)×10−3, B(τ−→π−KS0ηντ)=(4.4±0.7±0.2)×10−5, and B(τ−→K∗−ηντ)=(1.34±0.12±0.09)×10−4. These results are substantially more precise than previous measurements. The new measurements are compared with theoretical calculations based on the CVC hypothesis or the chiral perturbation theory. We also set upper limits on branching fractions for τ decays into K−KS0ηντ, π−KS0π0ηντ, K−ηηντ, π−ηηντ and non-resonant K−π0ηντ final states.
We search for lepton flavor violating τ decays into three leptons (electron or muon) using 535 fb−1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. No evidence ...for these decays is observed, and we set 90% confidence level upper limits on the branching fractions of (2.0–4.1)×10−8. These results improve upon our previously published upper limits by factors of 4.9 to 10.
Theoretical predictions on angular correlations using the Double Log Approximation (DLA) of QCD are compared to experimental results from
e
+
e
− annihilation into hadrons at the LEP collider ...(DELPHI-Experiment).
We report a precise measurement of the masses of the Ξc(2645) and Ξc(2815) baryons using a data sample of 414 fb−1 collected by the Belle Collaboration at the KEKB e+e− collider. The states ...Ξc(2645)0,+ are observed in the Ξc+,0π−,+ decay modes, while the Ξc(2815)0,+ are reconstructed in the Ξc(2645)+,0π−,+ decay modes. The following mass splittings are determined: mΞc(2645)+−mΞc(2645)0=(−0.1±0.3(stat)±0.6(syst)) MeV/c2 and mΞc(2815)+−mΞc(2815)0=(−3.4±1.9(stat)±0.9(syst)) MeV/c2 with a much better precision than the current world averages. We also observe a new decay mode, Ξc(2980)0,+→Ξc(2645)+,0π−,+.
PDF
