The decay τ−→K−KSντ has been studied using 430×106 e+e−→τ+τ− events produced at a center-of-mass energy around 10.6 GeV at the PEP-II collider and studied with the BABAR detector. The mass spectrum ...of the K−KS system has been measured and the spectral function has been obtained. The measured branching fraction B(τ−→K−KSντ)=(0.739±0.011(stat)±0.020(syst))×10−3 is found to be in agreement with earlier measurements.
We use 429 fb$^{-1}$ of $e^+e^-$ collision data collected at the $\Upsilon(4S)$ resonance with the BABAR detector to measure the radiative transition rate of $b\rightarrow s\gamma$ with a sum of 38 ...exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be $\mathcal{B}(\bar B \rightarrow X_{s}\gamma)=(3.29\pm 0.19\pm 0.48)\times 10^{-4}$ where the first uncertainty is statistical and the second is systematic. We also measure the first and second moments of the photon energy spectrum and extract the best fit values for the heavy-quark parameters, $m_{b}$ and $\mu_{\pi}^{2}$, in the kinetic and shape function models.
We search for evidence of a light scalar boson in the radiative decays of the Υ ( 2 S ) and Υ ( 3 S ) resonances: Υ ( 2 S , 3 S ) → γ A 0 , A 0 → μ + μ − . Such a particle appears in extensions of ...the standard model, where a light C P -odd Higgs boson naturally couples strongly to b quarks. We find no evidence for such processes in the mass range 0.212 ≤ m A 0 ≤ 9.3 GeV in the samples of 99 × 10 6 Υ ( 2 S ) and 122 × 10 6 Υ ( 3 S ) decays collected by the BABAR detector at the SLAC PEP-II B factory and set stringent upper limits on the effective coupling of the b quark to the A 0 . We also limit the dimuon branching fraction of the η b meson: B ( η b → μ + μ − ) < 0.9 % at 90% confidence level.
Evidence of B + → τ + ν decays with hadronic B tags Grauges, E.; Palano, A.; Eigen, G. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
08/2013, Letnik:
88, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We present a search for the decay B + → τ + ν using 467.8 × 10 6 B ¯¯¯ B pairs collected at the Υ ( 4 S ) resonance with the BABAR detector at the SLAC PEP-II B -Factory. We select a sample of events ...with one completely reconstructed B − in the hadronic decay mode ( B − → D ( * ) 0 X − and B − → J / ψ X − ). We examine the rest of the event to search for a B + → τ + ν decay. We identify the τ + lepton in the following modes: τ + → e + ν ¯ ν , τ + → μ + ν ¯ ν , τ + → π + ¯ ν and τ + → ρ + ¯ ν . We find an excess of events with respect to the expected background, which excludes the null signal hypothesis at the level of 3.8 σ (including systematic uncertainties) and corresponds to a branching fraction value of B ( B + → τ + ν ) = ( 1.83 + 0.53 − 0.49 ( stat ) ± 0.24 ( syst ) ) × 10 − 4 .
We study the process e+e−→π+π−ηγ, where the photon is radiated from the initial state. About 8000 fully reconstructed events of this process are selected from the BABAR data sample with an integrated ...luminosity of 469 fb−1. Using the π+π−η invariant mass spectrum, we measure the e+e−→π+π−η cross section in the e+e− center-of-mass energy range from 1.15 to 3.5 GeV. The cross section is well described by the Vector-Meson dominance model with four ρ-like states. We observe 49±9 events of the J/ψ decay to π+π−η and measure the product ΓJ/Ψ→e+e−BJ/Ψ→π+π−η=2.34±0.43stat±0.16syst eV.
Search for the decay modes B ± → h ± τ ℓ Grauges, E.; Milanes, D. A.; Schroeder, T. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
07/2012, Letnik:
86, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We present a search for the lepton flavor violating decay modes B+/- to h+/- tau l (h= K,pi; l= e,mu) using the BaBar data sample, which corresponds to 472 million BBbar pairs. The search uses events ...where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and l candidates, we are able to fully determine the tau four-momentum. The resulting tau candidate mass is our main discriminant against combinatorial background. We see no evidence for B+/- to h+/- tau l decays and set a 90% confidence level upper limit on each branching fraction at the level of a few times 10^-5.
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