arXiv subjects

B. Aubert

Publications and source records attributed to B. Aubert.

At least 613 records · Page 34Linked to original sources

arXiv2001

Measurement of B-->K*gamma Branching Fractions and Charge Asymmetries

The branching fractions of the exclusive decays $B^0\to K^{*0}γ$ and $B^+ \to K^{*+}γ$ are measured from a sample of $(22.74\pm 0.36)\times 10^6$ $B\bar B$ decays collected with the BABAR detector at the PEP II asymmetric $e^{+}e^{-}$ collider. We find ${\cal B}(B^0\to K^{*0}γ) = (4.23\pm 0.40({\rm stat.})\pm 0.22({\rm sys.}))\times 10^{-5}$, ${\cal B}(B^+\to K^{*+}γ) = (3.83\pm 0.62({\rm stat.})\pm 0.22({\rm sys.}))\times 10^{-5}$ and constrain the CP-violating charge asymmetry to be $-0.170 < A_{CP}(B \to K^*γ) < 0.082$ at 90% C.L.

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arXiv2001

Study of B-->D()anti-D() decays with the BABAR detector

Decays of the type B-->D(*)anti-D(*) can be used to provide a measurement of the parameter sin2beta of the Unitarity Triangle that is complementary to that derived from the mode \bpsiks. Here we report a measurement of the branching fraction and a study of the CP parity content for the decay B^0 --> D^{*+}D^{*-} with the BABAR detector. With data corresponding to an integrated luminosity of 20.7 fb^{-1} collected at the Upsilon(4S) resonance during 1999-2000, we determine the branching fraction to be BF(B^0-->D^{*+}D^{*-})=(8.0 +/- 1.6 (stat) +/- 1.2 (syst)) x 10^{-4}. The measured fraction of the component with odd CP parity is 0.22 +/- 0.18(stat) +/- 0.03(syst). Observation of a significant number of candidates in the decay modes B^0-->D^{*+}D^- and B^+ --> D^{*+}D^{*0} is reported. All results presented in this note are preliminary.

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arXiv2001

Search for B Decays into K0-anti-K0

We present preliminary results of a search for B0-->K0-anti-K0 decays in the K0SK0S final state using a sample of approximately 23 million B-anti-B pairs collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. We find no evidence for a signal and set an upper limit on the branching fraction of 7.3 x 10^{-6} at the 90% confidence level.

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arXiv2001

Search for Direct CP Violation in Quasi-Two-Body Charmless B Decays

We have searched for direct CP violation in quasi-two-body charmless B decays observed in a sample of about 45 million B mesons collected with the BABAR detector at the PEP-II collider. We measure the following charge asymmetries in decay: ${\cal A}_{CP} (B^{\pm}\toη^\prime K^{\pm}) = -0.11\pm 0.11\pm 0.02$, ${\cal A}_{CP} (B^{\pm}\toωπ^{\pm}) = -0.01^{+0.29}_{-0.31}\pm 0.03$, ${\cal A}_{CP} (B^{\pm}\toϕK^{\pm}) = -0.05\pm 0.20\pm 0.03$, ${\cal A}_{CP} (B^{\pm}\toϕK^{*\pm}) = -0.43^{+0.36}_{-0.30}\pm 0.06$, and ${\cal A}_{CP} (B^{0}/\bar B^{0}\toϕK^{*0}/\bar K^{*0}) = 0.00\pm 0.27\pm 0.03$.

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arXiv2001

Measurement of the Branching Fraction for B^+ --> K^{*0} pi^+

We present a preliminary result of the branching fraction for the B meson decay to the final state K^+pi^-pi^+ via an intermediate K^{*0} resonance using the sample of approximately 23 million B-anti-B mesons produced at the Upsilon(4S) resonance with the BABAR detector at the PEP II e+e- collider. The K^{*0} was detected through the decay to the final state K^+pi^-. The result of this analysis is BF(B^+ --> K^{*0} pi^+) = (15.5 +/- 3.4 +/- 1.8) x 10^{-6} where the first error is statistical and the second is systematic.

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arXiv2001

Search for a Lifetime Difference in D^0 Decays

The D^0 mixing parameter y = Delta Gamma/2 Gamma was determined by measuring the D^0 lifetime separately for the K^-pi^+ decay mode and the K^-K^+ decay mode with 12.4 fb^{-1} of data collected by the BABAR experiment in 2001. Backgrounds were suppressed with the D^* --> D^0pi^+ decay and particle identification. The following preliminary result was obtained: y = (-1.0 +/- 2.2 (stat) +/- 1.7 (syst))%.

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arXiv2001

Investigation of B --> D^{()}anti-D^{()}K decays with the BABAR detector

Using about 23M $B \bar B$ events collected in 1999-2000 with the BABAR detector, we report the observation of several hundred $B \to D^{(*)}\bar D^{(*)}K$ decays with two completely reconstructed D mesons. The preliminary branching fractions of the low background decay modes $B^0\to D^{*-}D^{(*)0}K^+$ are determined to be ${\cal B}(B^0 \to D^{*-}D^{0}K^+) = (2.8 \pm 0.7 \pm 0.5)\times 10^{-3}$ and ${\cal B}(B^0 \to D^{*-}D^{*0}K^+) = (6.8 \pm 1.7 \pm 1.7)\times 10^{-3}$. Observation of a significant number of candidates in the color-suppressed decay mode $B^+\to D^{*+}D^{*-}K^+$ is reported with a preliminary branching fraction ${\cal B}(B^+\to D^{*+}D^{*-}K^+)= (3.4\pm 1.6\pm 0.9)\times 10^{-3}.$

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arXiv2001

Study of CP-violating asymmetries in B-->pi^+/-pi^-/+, K^+/-pi^-+ decays

We present a preliminary measurement of the time-dependent CP-violating asymmetry parameters S_pipi and C_pipi in neutral B decays to the pi^+/-pi^-/+ CP eigenstate, and an updated preliminary measurement of the charge asymmetry A_Kpi in B --> K^+/-pi^-/+ decays. Event yields and $\CP$-violation parameters are determined simultaneously from a multidimensional unbinned maximum likelihood fit. In a data sample consisting of approximately 33 million Upsilon(4S)--)B-anti-B decays collected with the BABAR detector at the SLAC PEP-II asymmetric B Factory, we find 65^{+12}_{-11} pi^+/-pi^-/+ and 217+/-18 K^+/-pi^-/+ candidates and measure S_pipi = 0.03^{+0.53}_{-0.56}+/-0.11, C_pipi = -0.25^{+0.45}_{-0.47}+/-0.14, and A_Kpi = -0.07+/-0.08+/-0.02, where the first error is statistical and the second is systematic.

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arXiv2001

Search for B^0 --> a_0^+(980)pi^-

We present preliminary results of a search for the decay B^0 --> a_0^+(980)pi^- among 22.7 million Upsilon(4S)-->B-anti-B pairs collected by the BABAR detector at PEP-II. Using improved background suppression techniques and optimal signal extraction for rare decay searches, an excess of events over expected background is observed at the level of 3.7 standard deviations. This corresponds to the branching fraction BR(B^0 --> a_0^+ (a_0^+ --> eta pi^+) pi^-) =(6.2_{-2.5}^{+3.0}+/-1.1) x 10^{-6}, where the first error is statistical and the second is systematic. The 90% confidence level upper limit is 11.5 x 10^{-6}.

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arXiv2001

Measurement of the branching fraction for the decay B^0 --> D^{+}D^{-}

Decays of the type B --> D^{(*)} anti-D^{(*)} can be used to provide a measurement of the parameter sin2beta of the Unitarity Triangle that is complementary to the measurement derived from the mode B^0 --> J/psi K_s^0. In this document we report a measurement of the branching fraction for the decay B^0 --> D^{*+}D^{*-} with the BABAR detector. With data corresponding to an integrated luminosity of 20.7 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+/-0.5 events. From these events, we determine the branching fraction to be BF(B^0 --> D^{*+}D^{*-}) = (8.0+/-1.6(stat)+/-1.2(syst))x10^{-4} (preliminary).

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arXiv2001

Measurements of B^0 decays to pi^+pi^-pi^0

We present preliminary results of searches for exclusive $B^0$ decays to $π^+π^-π^0$ among 22.7 million $b\bar{b}$ pairs collected by the BABAR experiment from electron-positron collisions near the $Υ(4S)$ resonance. We measure $\cal{B}(ρ^\mp π^\pm) = (28.9\pm 5.4\pm 4.3)\times 10^{-6}$, and find no evidence for the presence of any other decay mode in the $π^+π^-π^0$ Dalitz plot. Upper limits are determined for the branching fractions of $B^0\toρ^0π^0$, non-resonant $B^0$ decays to $π^+π^-π^0$ and of several discrete regions of $π^+π^-π^0$ phase-space. We also measure the direct CP-violating asymmetry between the rates of untagged $ρ^+π^-$ and $ρ^-π^+$, finding no significant evidence for an effect.

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arXiv2001

Study of T and CP violation in B^0-anti-B^0 mixing with inclusive dilepton events

We report a study of T and CP violation in $B^0$-$\bar B^0$ mixing using an inclusive dilepton sample collected by the BABAR experiment at the PEP-II $B$ Factory. The asymmetry between $\ell^+\ell^+$ and $\ell^-\ell^-$ allows us to compare the probabilities for $\bar B^0 \to B^0$ and $B^0 \to \bar B^0$ oscillations and thus probe T and CP invariance. A sample of 20,381 same-sign dilepton events is selected in the 1999--2000 data sample, corresponding to an integrated luminosity of 20.7 fb$^{-1}$ on the $Υ(4S)$ resonance. We measure a same-sign dilepton asymmetry of $A_T=(0.5\pm 1.2\pm 1.4)%$; for the parameter $ε_b$ representing T and CP violations in mixing, we obtain a preliminary result of $$ \frac{{\mathrm Re}(ε_b)}{1+|ε_b|^2} = (1.2\pm 2.9\pm 3.6) \times 10^{-3}. $$

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arXiv2001

Measurement of D_s^+ and D_s^{*+} production in B meson decays and from continuum e^+e^- annihilations at sqrt{s}=10.6 GeV

New precise measurements of $D_s^+$ and $D_s^{*+}$ meson production from $B$ mesons and $q\bar q$ continuum events near the $Υ(4S)$ resonance are presented in this paper. Using the BABAR data recorded in 1999 and 2000 of 20.8 fb$^{-1}$ on-resonance and 2.6 fb$^{-1}$ off-resonance, we measure the inclusive branching fractions ${\cal B}(B\to D_s^+ X) = (10.93\pm 0.19\pm 0.58\pm 2.73)%$ and ${\cal B}(B\to D_s^{*+} X) = (7.94\pm 0.82\pm 0.72\pm 1.99)%$, where the first error is statistical, the second is the systematic error, and the third is the error due to the $D_s^+\toϕπ^+$ branching fraction uncertainty. The branching fractions $Σ{\cal B}(B\to D_s^{(*)+} \bar D^{(*)}) = (5.07\pm 0.09\pm 0.34\pm 1.27)%$ and $Σ{\cal B}(B\to D_s^{*+} \bar D^{(*)}) = (4.07\pm 0.42\pm 0.53\pm 1.02)%$ have been determined from the measured $D_s^{(*)+}$ momentum spectra.

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arXiv2001

Measurement of the B-->J/psi K^*(892) decay amplitudes

We present a measurement of the decay amplitudes in B-->J/psi K^*(892) channels using 20.7 fb-1 of data collected at the Upsilon(4S) resonance with the BABAR detector at PEP-II. We measure a P-wave fraction R_perp = (16.0+/-3.2+/-1.4)% and a longitudinal polarization fraction (59.7+/-2.8+/-2.4)%. The measurement of a relative phase that is neither 0 nor pi, phi_ll = 2.50+/-0.20+/-0.08 radians, favors a departure from the factorization hypothesis. Although the decay B-->J/psi Kpi proceeds mainly via K^*(892), there is also evidence for K^*_2(1430) and Kpi S-wave contributions.

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arXiv2001

Search for the Rare Decays B --> Kl^+l^- and B --> K^*(892)l^+ l^-

We present preliminary results from a search for the flavor-changing neutral current decays B-->Kl^+l^- and B-->K^*(892)l^+l^- using a sample of 22.7 x 10^6 Upsilon(4S)-->B anti-B decays collected with the BABAR detector at the PEP-II B Factory. We have reconstructed the following final states: B^+ --> K^+l^+l^-, B^0 --> K^0l^+l^- (K_s^0 --> pi^+pi^-), B^+ --> K^{*+}l^+l^- (K^{*+} --> K_s^0 pi^+), and B^0 --> K^{*0}l^+l^- (K^{*0} --> K^+pi^-), where l^+l^- is either an e^+e^- or mu^+mu^- pair. We obtain the 90% C.L. upper limits BF(B --> Kl^+l^-)< 0.6 x 10^{-6} and BF(B --> K^*l^+l^-)<2.5 x 10^{-6}, close to the Standard Model predictions for these branching fractions.

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arXiv2001

Measurement of the B^0-anti-B^0 oscillation frequency in hadronic B^0 Decays

B^0-anti-B^0 flavor oscillations have been studied in 20.7 fb-1 of e^+e^- annihilation data collected in 1999 and 2000 with the BABAR detector at center-of-mass energies near the Upsilon(4S) resonance. The event sample consists of one B^0 meson fully reconstructed in a hadronic decay mode, while the flavor of the recoiling B^0 in the event is determined with a tagging algorithm that exploits the correlation between the flavor of the heavy quark and the charges of its decay products. By fitting the time development of the observed mixed and unmixed final states, the B^0-anti-B^0 oscillation frequency, Delta_md, is determined to be 0.519+/- 0.020+/- 0.016 ps^{-1}.

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arXiv2001

Measurement of the exclusive branching fractions B^0 --> eta K^{0) and B^+ --> eta K^{+}

We present the results of searches for B decays to the two charmless two-body final states B^0 --> eta K^{*0} and B^+ --> eta K^{*+}, based on 20.7 fb-1 of data collected in 1999 and 2000 with the BABAR detector at PEP-II. We find the branching fractions BF(B^0 --> eta K^{*0}) = (19.8^{+6.5}_{-5.6} +/- 1.7) x 10^{-6} and BF(B^+ --> eta K^{*+}) = (22.1^{+11.1}_{-9.2} +/- 3.3) x 10^{-6}, where the first error quoted is the statistical and the second systematic.

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arXiv2001

Measurement of branching fractions for exclusive B decays to charmonium final states

We report branching fraction measurements for exclusive decays of charged and neutral B mesons into two-body final states containing a charmonium meson. We use a sample of 22.72 +/- 0.36 million B anti-B events collected between October 1999 and October 2000 with the BABAR detector at the PEP-II storage rings at the Stanford Linear Accelerator Center. The charmonium mesons considered here are J/psi, psi(2S), and chi_c1, and the light meson in the decay is either a K, K^*, or pi^0.

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