45 research outputs found

    Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

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    The B0B^0-Bˉ0\bar B^0 oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives Δmd=0.493±0.012(stat)±0.009(syst)\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)} ps−1^{-1}.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

    The Physics of the B Factories

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    The BaBar detector: Upgrades, operation and performance

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    Contains fulltext : 121729.pdf (preprint version ) (Open Access

    Measurement of B0−Bˉ0B^0-\bar B^0 flavor oscillations in hadronic B0B^0 Decays

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    We have studied the B^+/- --> J/psi pi^+/- and B^+/- --> J/psi K^+/- decays using a 20.7 fb-1 data set collected with the BABAR detector. We observe a signal of 51+/-10 B^+/- --> J/psi pi^+/- events and determine the ratio BF(B^+/- --> J/psi pi^+/-)/BF(B^+/- --> J/psi K^+/-) to be [3.91 +/- 0.78 (stat.) +/- 0.19 (syst.)]%. The CP-violating charge asymmetries for the B^+/- --> J/psi pi^+/- and B^+/- --> J/psi K^+/- decays are determined to be A_pi = 0.01 +/- 0.22 (stat.) +/- 0.01 (syst.) and A_K = 0.003 +/- 0.030 (stat.) +/- 0.004 (syst.)

    Search for the rare decays B→Kl+l−B \to Kl^+l^- and B→K∗l+l−B \to K^*l^+l^-

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    We present results from a search for the flavor-changing neutral current decays B→Kℓ+ℓ−B\to K\ell^+\ell^- and B→K∗ℓ+ℓ−B\to K^*\ell^+\ell^-, where ℓ+ℓ−\ell^+\ell^- is either an e+e−e^+e^- or ÎŒ+Ό−\mu^+\mu^- pair. The data sample comprises 22.7×10622.7\times 10^6 ΄(4S)→BBˉ\Upsilon(4S)\to B\bar B decays collected with the BABAR detector at the PEP-II BB Factory. We obtain the 90% C.L. upper limits B(B→Kℓ+ℓ−)<0.50×10−6{\mathcal B}(B\to K\ell^+\ell^-)< 0.50\times 10^{-6} and B(B→K∗ℓ+ℓ−)<2.9×10−6{\mathcal B}(B\to K^*\ell^+\ell^-)<2.9\times 10^{-6}, close to Standard Model predictions for these branching fractions. We have also obtained limits on the lepton-family-violating decays B→Ke±Ό∓B\to Ke^{\pm}\mu^{\mp} and B→K∗e±Ό∓B\to K^{*}e^{\pm}\mu^{\mp}
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