Using the ARGUS detector at the
e
+
e
− storage ring DORIS II, we have searched for the real and imaginary part of the electric dipole formfactor
d
τ
of the
τ lepton in the production of
τ pairs at
q
...2=100
GeV
2
. This is the first direct measurement of this
CP
violating formfactor. We applied the method of optimised observables which takes into account all available information on the observed
τ decay products. No evidence for
CP
violation was found, and we derive the following results:
Re(d
τ)=(1.6±1.9)·10
−16
e
cm
and
Im(d
τ)=(−0.2±0.8)·10
−16
e
cm
, where statistical and systematic errors have been combined.
We report first observations of Bs0→J/ψη and Bs0→J/ψη'. The results are obtained from 121.4 fb⁻¹ of data collected at the Υ(5S) resonance with the Belle detector at the KEKB e⁺e⁻ collider. We obtain ...the branching fractions B(Bs0→J/ψη)=5.10±0.50(stat)±0.25(syst)+1.14-0.79(NB(*)sB¯¯¯(*)s)×10⁻⁴, and B(Bs0→J/ψη')=3.71±0.61(stat)±0.18(syst)+0.83-0.57(NB(*)sB¯¯¯(*)s)×10⁻⁴. The ratio of the two branching fractions is measured to be (B(Bs→J/ψη'))/(B(Bs→J/ψη))=0.73±0.14(stat)±0.02(syst).
Here, we report the result from the first search for D0 decays to invisible final states. The analysis is performed on a data sample of 924fb-1 collected at and near the Υ ( 4S ) and Υ ( 5S ) ...resonances with the Belle detector at the KEKB asymmetric-energy e+e- collider. The absolute branching fraction is confirmed using an inclusive D0 sample, obtained by fully reconstructing the rest of the particle system including the other charmed particle. No significant signal yield is observed and an upper limit of 9.4×10-5 is set on the branching fraction of D0 to invisible final states at 90% confidence level.
We report a measurement of the ratio R(D*)=B($\bar{B}$0→D*+τ-$\bar{v}$$\bar{τ}$)/B($\bar{B}$0→D*+ℓ-$\bar{v}$ℓ), where ℓ denotes an electron or a muon. The results are based on a data sample ...containing 772×106 B$\bar{B}$ pairs recorded at the Υ(4S) resonance with the Belle detector at the KEKB e+e- collider. We select a sample of B0$\bar{B}$0 pairs by reconstructing both B mesons in semileptonic decays to D*∓ℓ±. We measure R(D*)=0.302±0.030(stat)±0.011(syst), which is within 1.6σ of the Standard Model theoretical expectation, where the standard deviation σ includes systematic uncertainties. We use this measurement to constrain several scenarios of new physics in a model-independent approach.
We report a measurement of the ratio R(D*) = B($\bar{B}$0→ D*+τ-$\bar{v}$τ )/B($\bar{B}$0→D*+ℓ-$\bar{v}$ℓ), where ℓ denotes an electron or a muon. The results are based on a data sample containing ...772 × 106 B$\bar{B}$ pairs recorded at the (4S) resonance with the Belle detector at the KEKB e+e- collider. We select a sample of B0 $\bar{B}$0pairs by reconstructing both B mesons in semileptonic decays to D*∓ℓ±. We measure R(D*) = 0.302±0.030(stat) ±0.011(syst), which is within 1.6σ of the Standard Model theoretical expectation, where the standard deviation σ includes systematic uncertainties. We use this measurement to constrain several scenarios of new physics in a model-independent approach.
Here, we report a measurement of the ratio R ( D* ) = B ( B ¯ 0 → D*+τ- ν ¯ τ ) / B ( B ¯ 0 → D*+ℓ- ν ¯ ℓ ) , where ℓ denotes an electron or a muon. The results are based on a data sample containing ...772×106B B ¯ pairs recorded at the Υ ( 4S ) resonance with the Belle detector at the KEKB e+e- collider. We select a sample of B0 B ¯ 0 pairs by reconstructing both B mesons in semileptonic decays to D*∓ℓ± . We measure R ( D* ) =0.302±0.030 ( stat ) ±0.011 ( syst ) , which is within 1.6σ of the Standard Model theoretical expectation, where the standard deviation σ includes systematic uncertainties. We use this measurement to constrain several scenarios of new physics in a model-independent technique.
Here, we show a measurement of the CP -violation parameter φ1 obtained in a time-dependent analysis of B0 → D ¯ ( * ) 0h0 decays followed by D ¯ 0 → KS0π+π- decay. A model-independent measurement is ...performed using the binned Dalitz plot technique. The measured value is φ1=11.7°±7.8° ( stat ) ±2.1° ( syst ) . Treating sin2φ1 and cos2φ1 as independent parameters, we obtain sin2φ1=0.43±0.27 ( stat ) ±0.08 ( syst ) and cos2φ1=1.06±0.33 ( stat ) -0.15+0.21 ( syst ) . The findings are obtained with a full data sample of 772×106B B ¯ pairs collected near the Υ ( 4S ) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
With data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider, we measure the energy dependence of the e+e- → hb ( nP ) π+π- ( n=1 , 2) cross sections from thresholds up to ...11.02 GeV. We find clear Υ ( 10860 ) and Υ ( 11020 ) peaks with little or no continuum contribution. We study the resonant substructure of the Υ ( 11020 ) → hb ( nP ) π+π- transitions and find evidence that they proceed entirely via the intermediate isovector states Zb ( 10610 ) and Zb ( 10650 ) . The relative fraction of these states is loosely constrained by the current data: The hypothesis that only Zb ( 10610 ) is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only Zb ( 10650 ) is produced is not excluded at a significant state.
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