arXiv subjects

B. Aubert

Publications and source records attributed to B. Aubert.

At least 595 records · Page 33Linked to original sources

arXiv2002

Measurements of the branching fractions of charmless three-body charged B decays

We present preliminary results of searches for charged B mesons decaying into the charmless three-body final states hhh, where h = pi or K, using 51.5 fb^-1 of data collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II asymmetric B Factory. No assumptions are made about intermediate resonances. We measure the branching fractions B(B+ -> K+ pi- pi+) = (59.2 +- 4.7 +- 4.9) x 10^-6 and B(B+ -> K+ K- K+) = (34.7 +- 2.0 +- 1.8) x 10^-6, where the first error is statistical and the second error is systematic. In the same study, we do not observe significant signals for the final states B+ -> pi+ pi- pi+ and B+ -> K+ K- pi+, and therefore provide the 90% confidence upper limits B(B+ -> pi+ pi- pi+) < 15 x 10^-6 and B(B+ -> K+ K- pi+) < 7 x 10^-6.

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arXiv2002

Evidence for the $b\to u$ Transition $B^0\to D_s^+ pi^-$ and a Search for $B^0\to D_s^*+ pi^-$

We report evidence for the $b\to u$ transition $B^0 \to D_s^{+}π^-$ and the results of a search for $B^0 \to D_s^{*+} π^-$ from a sample of $61.6\times 10^6$ $Y(4S)$ decays into $B$ meson pairs collected with the BaBar detector at the PEP II asymmetric $e^{+}e^{-}$ collider. The observed $B^0 \to D_s^{+} π^-$ yield has a probability of $4.4 \times 10^{-4}$ to be a fluctuation of the background (3.5 $σ$) and we measure the branching fraction $B^0 \to D_s^{+} π^-=3.1 \pm 1.0 ({\rm stat.})\pm 1.0 ({\rm syst.})$. We also set a limit $B^0 \to D_s^{*+} π^- <~4.3\times 10^{-5}$ at 90% C.L.

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arXiv2002

Measurements of Branching Fractions and CP-Violating Asymmetries in B0 --> pi+pi-, K+pi-, K+K- Decays

We present updated measurements of branching fractions and CP-violating asymmetries for neutral B meson decays to two-body final states of charged pions and kaons. The results are obtained from a data sample of about 60 million Y(4S) --> B-anti-B decays collected between 1999 and 2001 by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The sample contains 124^{+16}_{-15} pi-pi, 403+/-24 K-pi, and 0.6^{+8.0}_{-7.4} K-K candidates, from which we measure the following quantities: BF(B0 --> pi+pi-) = (5.4+/-0.7+/-0.4) x 10^{-6}, BF(B0 --> K+pi-) = (17.8+/-1.1+/-0.8) x 10^{-6}, BF(B0 --> K+K-) < 1.1 x 10^{-6} (90% C.L.} A_Kpi = -0.05+/-0.06+/-0.01 [-0.14,+0.05], S_pipi = -0.01+/-0.37+/-0.07 [-0.66,+0.62], C_pipi = -0.02+/-0.29+/-0.07 [-0.54,+0.48], where the errors are statistical and systematic, respectively, and the asymmetry limits correspond to the 90% confidence level. These results are preliminary.

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arXiv2002

A study of B^+/- --> J/psi pi^+/- and B^+/- --> J/psi K^+/- decays: measurement of the ratio of branching fractions and search for direct CP-violating charge asymmetries

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.).

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arXiv2002

Branching Fraction Measurements of the Decays B -> EtaC K, where EtaC -> KKbarPi and EtaC -> 4K

In this report, we present the observation of the exclusive decays B0 -> EtaC K0 and B+ -> EtaC K+, and the measurement of the related branching fractions. Using a sample of 22.7x10^6 Upsilon(4S) -> BBbar decays collected with the BABAR detector at the SLAC PEP-II asymmetric B Factory during 1999-2000, we have observed statistically significant signals in the EtaC -> KsK+Pi- and K+K-Pi0 channels and set upper limits in the EtaC -> K+K-K+K- channels. All the results presented are preliminary. We have measured BF(B+ -> EtaC K+) = (1.50 +/- 0.19 +/- 0.15 +/- 0.46)x10^{-3} BF(B0 -> Etac K0) = (1.06 +/- 0.28 +/- 0.11 +/- 0.33)x10^{-3} where the first error is statistical, the second systematic and the last due to the uncertainty on the world average EtaC -> KKbarPi branching fraction.

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arXiv2002

A Measurement of the Neutral B Meson Lifetime using Partially Reconstructed B0 --> D*-pi+ Decays

The neutral B meson lifetime has been measured with the data collected by the BABAR detector at the PEP-II storage ring during the year 2000 for a total integrated luminosity of 20.3 fb-1. The B0 --> D*- pi+ decays have been selected with a partial reconstruction method in which only the fast pion from the B0 decay and the slow pion from D*- --> D0 bar pi- are reconstructed. The B0 lifetime has been measured to be 1.510 +/- 0.040 +/- 0.038 ps with a sample of 6971 +/- 241 reconstructed signal events.

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arXiv2002

A Measurement of the B0 --> J/psi pi+pi- Branching Fraction

We present a preliminary measurement of the branching fraction for the decay of the neutral $B$ meson into the final state J/$ψπ^+π^-$. The data set contains approximately 56 million $B\bar{B}$ pairs produced at the $Υ(4S)$ resonance and recorded by the BaBar detector at the PEP-II $e^+e^-$ collider. The result of this analysis is $\mathcal{B}(B^0\to J/ψπ^+π^-$) = (5.0 $\pm$ 0.7 $\pm$ 0.6)$\times 10^{-5}$, where the first error is statistical and the second is systematic.

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arXiv2002

Rare B Decays to States Containing a J/psi Meson

We report preliminary measurements of the branching fractions for B+ -> J/psi phi K+, B0 -> J/psi phi K0S, B0 -> J/psi phi, B0 -> J/psi eta and B -> J/psi eta' using 56 million BBbar events collected at the Y(4S) resonance with the BABAR detector at PEP-II. We measure branching fractions of B(B+ -> J/psi phi K+)=(4.4+-1.4(stat)+-0.7(syst))*10^-5 and B(B0 -> J/psi phi K0S)=(5.1+-1.9(stat)+-0.9(syst))*10^-5, and set upper limits at 90% C.L. for branching fractions, B(B -> J/ψphi)< 0.95*10^-5, B(B -> J/ψeta)< 2.7*10^-5, and B(B -> J/ψeta')< 6.4*10^-5.

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arXiv2002

Measurement of the B0 Lifetime with Partial Reconstruction of B0bar -> D*+ rho-

A sample of about 5500 $\bar B^0 \to D^{*+} ρ^-$ and 700 $\bar B^0 \to D^{*+} a_1^-$ events is identified, using the technique of partial reconstruction, among 22.7 $B\bar B$ pairs collected by the BaBar experiment at the PEP-II storage ring. With these events, the $B^0$ lifetime is measured to be $1.616 \pm 0.064 \pm 0.075$ ps. This measurement serves as validation for the procedures required to measure $\sin(2β+ γ)$ with partial reconstruction of $\bar B^0 \to D^{*+} ρ^-$.

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arXiv2002

Improved measurement of the CP-violating asymmetry amplitude sin2beta

We present updated results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 62 million Upsilon(4S) --> B anti-B decays collected between 1999 and 2001 by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. In this sample we study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2beta, is derived from the decay time distributions in such events. We measure sin2beta = 0.75 +/- 0.09 (stat) +/- 0.04 (syst) and |λ| = 0.92 +/- 0.06 (stat) +/- 0.02 (syst). The latter is consistent with the Standard Model expectation of no direct CP violation. These results are preliminary.

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arXiv2002

Measurement of the Branching Fraction and CP Content for the Decay B0 --> D+ D-

We report a measurement of the branching fraction of the decay B^0 --> D^{*+} D^{*-} and of the CP-odd component of its final state using the BaBar detector. With data corresponding to an integrated luminosity of 20.4 fb^{-1} collected at the Upsilon(4S) resonance during 1999-2000, we have reconstructed 38 candidate signal events in the mode B^0 --> D^{*+}D^{*-} with an estimated background of 6.2 \pm 0.5 events. From these events, we determine the branching fraction to be BR(B^0 --> D^{*+}D^{*-}) = (8.3 +/- 1.6(stat) +/- 1.2(syst)) x 10^{-4}. The measured CP-odd fraction of the final state is 0.22 +/- 0.18(stat) +/- 0.03(syst).

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arXiv2002

Search for T and CP Violation in B0-anti-B0 Mixing with Inclusive Dilepton Events

We report the results of a search for T and CP violation in B0-anti-B0 mixing using an inclusive dilepton sample collected by the BaBar experiment at the PEP-II B Factory. The asymmetry between (l+,l+) and (l-,l-) events allows us to compare the probabilities P(anti-B0 -> B0) and P(B0 -> anti-B0) oscillations and thus probe T and CP invariance. Using a sample of 23 million B-anti-B pairs, we measure a same-sign dilepton asymmetry of A_(T/CP)=(0.5 +- 1.2(stat) +- 1.4(syst))%. For the modulus of the ratio of complex mixing parameters p and q, we obtain |q/p| = 0.998 +- 0.006(stat) +- 0.007(syst).

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arXiv2002

Measurement of the B0 Lifetime with Partially Reconstructed B0 --> D*- l+ nu Decays

The B0 lifetime has been measured with a sample of 23 million BBbar pairs collected by the BaBar detector at the PEP-II e+e- storage ring during 1999 and 2000. Events from the semileptonic decay B0 --> D*- l+ nu have been selected with a partial reconstruction method in which only the charged lepton and the slow pion from the D*- --> D0bar pi- decay are reconstructed. The result is tau_B0 = 1.529+/-0.012 (stat) +/- 0.029 (syst) ps.

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arXiv2002

Measurement of Ds+ and Ds*+ Production in B Meson Decays and from Continuum e+e- Annihilation at sqrt{s}=10.6 GeV

New measurements of Ds+ and Ds*+ meson production rates from B decays and from qqbar continuum events near the Y(4S) resonance are presented. Using 20.8 fb-1 of data on the Y(4S) resonance and 2.6 fb-1 off resonance, we find the inclusive branching fractions BR(B --> Ds+ X) = (10.93+/-0.19+/-0.58+/-2.73)% and BR(B --> Ds*+ X) = (7.9+/-0.8+/-0.7+/-2.0)%, where the first error is statistical, the second is systematic, and the third is due to the Ds+ --> phi pi+ branching fraction uncertainty. The branching fractions SumBR(B --> Ds(*)+ Dbar(*)) = (5.07+/-0.14+/-0.30+/-1.27)% and SumBR(B --> Ds*+ Dbar(*)) = (4.1+/-0.2+/-0.4+/-1.0)% are determined from the Ds(*)+ momentum spectra.

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arXiv2002

A Study of Time-Dependent CP-Violating Asymmetries and Flavor Oscillations in Neutral B Decays at the Upsilon(4S)

We present a measurement of time-dependent CP-violating asymmetries in neutral B meson decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The data sample consists of 29.7 ${\rm fb}^{-1}$ recorded at the $Υ(4S)$ resonance and 3.9 ${\rm fb}^{-1}$ off-resonance. One of the neutral B mesons, which are produced in pairs at the $Υ(4S)$, is fully reconstructed in the CP decay modes $J/ψK^0_S$, $ψ(2S) K^0_S$, $χ_{c1} K^0_S$, $J/ψK^{*0}$ ($K^{*0}\to K^0_Sπ^0$) and $J/ψK^0_L$, or in flavor-eigenstate modes involving $D^{(*)}π/ρ/a_1$ and $J/ψK^{*0}$ ($K^{*0}\to K^+π^-$). The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. The proper time elapsed between the decays is determined by measuring the distance between the decay vertices. A maximum-likelihood fit to this flavor eigenstate sample finds $Δm_d = 0.516\pm 0.016 {\rm (stat)} \pm 0.010 {\rm (syst)} {\rm ps}^{-1}$. The value of the asymmetry amplitude $\sin2β$ is determined from a simultaneous maximum-likelihood fit to the time-difference distribution of the flavor-eigenstate sample and about 642 tagged $B^0$ decays in the CP-eigenstate modes. We find $\sin2β=0.59\pm 0.14 {\rm (stat)} \pm 0.05 {\rm (syst)}$, demonstrating that CP violation exists in the neutral B meson system. (abridged)

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arXiv2001

Measurement of B0-anti-B0 Flavor Oscillations in Hadronic B0 Decays

Flavor oscillations of neutral $B$ mesons have been studied in $e^+e^-$ annihilation data collected with the BABAR detector at center-of-mass energies near the $Υ(4S)$ resonance. The data sample used for this purpose consists of events in which one $B^0$ meson is reconstructed in a hadronic decay mode, while the flavor of the recoiling $B^0$ is determined with a tagging algorithm that exploits the correlation between the flavor of the heavy quark and the charges of its decay products. From the time development of the observed mixed and unmixed final states we determine the $B^0$-$\bar B^0$ oscillation frequency $Δm_d$ to be $0.516 \pm 0.016 ({stat}) \pm 0.010 ({syst}) {\rm ps}^{-1}$.

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arXiv2001

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

The $B^0$-$\bar B^0$ 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 $Δm_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.

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arXiv2001

Direct CP Violation Searches in Charmless Hadronic B Meson Decays

We search for direct CP violation in charmless hadronic B decays observed in a sample of about 22.7 million $B\bar{B}$ pairs collected with the BABAR detector at the PEP-II asymmetric-energy $e^+e^-$ collider. We measure the following charge asymmetries: ${\cal A}_{CP} (B^{\pm}\toη^\prime K^{\pm}) = -0.11\pm 0.11\pm 0.02$, ${\cal A}_{CP} (B^{\pm}\toωπ^{\pm}) = -0.01^{+0.29}_{-0.31}\pm 0.03$, ${\cal A}_{CP} (B^{\pm}\toϕK^{\pm}) = -0.05\pm 0.20\pm 0.03$, ${\cal A}_{CP} (B^{\pm}\toϕK^{*\pm}) = -0.43^{+0.36}_{-0.30}\pm 0.06$, and ${\cal A}_{CP} (B^{0}\toϕK^{*0}) = 0.00\pm 0.27\pm 0.03$.

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