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The BABAR Collaboration

Publications and source records attributed to The BABAR Collaboration.

At least 505 records · Page 28Linked to original sources

arXiv2003

Study of Time-Dependent CP Asymmetries with Partial Reconstruction of B -> D*+ pi-

We present a preliminary measurement of the time-dependent CP asymmetries in decays of neutral B mesons to the final states D*pi using approximately 82 million BBbar events collected by the BaBar experiment at the PEPII storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high momentum pion and the low momentum pion from the D* decay are reconstructed. The flavor of the other B meson in the event is tagged using the information from kaon and lepton candidates. We measure the time-dependent CP asymmetry A = -0.063 +/- 0.024 (stat.) +/- 0.017 (syst.). We interpret these results in terms of the angles of the unitarity triangle to set a bound on |sin(2 beta + gamma)|.

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arXiv2003

Measurement of Time-Dependent CP Asymmetries and the CP-Odd Fraction in the Decay B0 --> D+D-

We present a measurement of time-dependent CP asymmetries and an updated determination of the CP-odd fraction in the decay B0 --> D*+D*- using a data sample of 88 x 10^6 BBbar pairs collected by the BABAR detector at the PEP-II B Factory at SLAC. We determine the CP-odd fraction to be 0.063 +/- 0.055(stat) +/- 0.009(syst). The time-dependent CP asymmetry parameters $Im(λ_+)$ and $|λ_+|$ are determined to be 0.05 +/- 0.29(stat) +/- 0.10(syst) and 0.75 +/- 0.19(stat) +/- 0.02(syst), respectively. The Standard Model predicts these parameters to be -sin2beta and 1, respectively, in the absence of penguin diagram contributions.

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arXiv2003

Measurement of the Branching Fraction and CP-violating Asymmetries in Neutral B Decays to D*+-D-+

We present measurements of the branching fraction and CP-violating asymmetries for neutral B decays to D*+-D-+. The measurement uses a data sample of approximately 88 million Y(4S) --> B Bbar decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. We measure the branching fraction to be (8.8 +- 1.0 +- 1.3) x 10^-4 and the time-integrated CP-violating asymmetry between the rates to D*+D- and D*-D+ to be A = -0.03 +- 0.11 +- 0.05. We also measure the time-dependent CP-violating asymmetry parameters to be S-+ = -0.24 +- 0.69 +- 0.12, C-+ = -0.22 +- 0.37 +- 0.10 for B --> D*-D+ and S+- = -0.82 +- 0.75 +- 0.14$, C+- = -0.47 +- 0.40 +- 0.12 for B --> D*+D-. In each case the first error is statistical and the second error is systematic.

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arXiv2003

A Study of Time-Dependent CP Asymmetry in B0 --> J/psi pi0 Decays

We present our first study of the time-dependent CP-violating asymmetry in B0 --> J/psi pi0 decays using e^+e^- annihilation data collected with the BABAR detector at the Y(4S) resonance during the years 1999--2002 at the PEP-II asymmetric-energy B Factory at SLAC. With about 88 million B Bbar pairs, our preliminary results for the coefficients of the cosine and sine terms of the CP asymmetry are C_{J/psi pi0} = 0.38 +/- 0.41 (stat) +/- 0.09 (syst) and S_{J/psi pi0} = 0.05 +/- 0.49 (stat) +/- 0.16 (syst).

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arXiv2003

Search for D0D0bar Mixing and a Measurement of the Doubly Cabibbo-suppressed Decay Rate in D0 -> K pi Decays

We present results of a search for $D^0$-$\kern 0.2em\bar{\kern -0.2em D}{}^0$~mixing and a measurement of $R_{\rm D}$, the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays, based on an analysis of $D^0 \to K^{+}π^{-}$ decays in 57.1~${fb}^{-1}$ of data collected at or just below the $Υ{(4S)}$ resonance with the {\slshape BABAR} detector at the PEP-II collider. Our results are compatible with no mixing and no $CP$ violation. At the 95% C.L., allowing for CP violation, we find the mixing parameters ${x^{\prime}}^2<0.0022$ and $-0.056<y^{\prime}<0.039$, and the mixing rate $R_{\rm M} < 0.16%$. In the limit of no mixing, $R_{\rm D} = (0.357 \pm 0.022 \hbox{(stat.)} \pm 0.027 \hbox{(syst.)})%$ and the $CP$~violating asymmetry \mbox{$A_{\rm D} = 0.095 \pm 0.061 \hbox{(stat.)} \pm 0.083 \hbox{(syst.)}$.}

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arXiv2003

Observation of B Meson Decays to eta pi and eta K

We present preliminary measurements of the B meson decays B+->etapi+, B+->etaK+, and B0->etaK0. The data were recorded with the BABAR detector at PEP II and correspond to 88.9 million BBbar pairs produced in e+e- annihilation through the Upsilon(4S) resonance. We find the branching fractions B(B+->etapi+) = (4.2 +1.0-0.9 +/- 0.3)x 10^-6 and B(B+->etaK+) = (2.8 +0.8-0.7 +/-0.2)x10^-6. We set a 90% CL upper limit of B(B0->etaK0) < 4.6x10^-6. The time-integrated charge asymmetries are Ach(B+->etapi+) = -0.51 +0.20-0.18 +/-0.01 and Ach(B+->etaK+) = -0.32 +0.22-0.18 +/-0.01.

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arXiv2003

Observation of B Meson Decays to omegapi+, omegaK+, and omegaK0

We present preliminary measurements of B meson decays to omegapi+, omegaK+, and omegaK0. The data were recorded with the BABAR detector and correspond to 88.9x10^6 BBbar pairs produced in e+e- annihilation at the Upsilon(4S) resonance. We find statistically significant signals for all three channels: B(B->omegapi+)=(5.4+/-1.0+/-0.5)x10^-6, B(B->omegaK+)=(5.0+/-1.0+/-0.4)x10^-6, and B(B->omegaK0)=(5.3^+1.4_-1.2+/-0.5)x10^-6. We also measure time-integrated charge asymmetries A_ch(omegapi+)=0.04+/-0.17+/-0.01 and A_ch(omegaK+)=-0.05+/-0.16+/-0.01.

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arXiv2003

Evidence for B+ --> Jpsi p Lambda-bar and Search for B0 --> Jpsi p p-bar

We have performed a search for the decays $B^+\to J/ψp \barΛ$ and $B^0\to J/psi p \bar{p}$ in a data set of $(88.9 \pm 1.0)\times 10^6$ $Υ(4S)$ decays collected by the BaBar experiment at the PEP-II $\e^+e^-$ storage ring at the Stanford Linear Accelerator Center. Four charged $B$ candidates have been observed with an expected background of $0.21\pm 0.14$ events. The corresponding branching fraction is $12^{+9}_{-6}\times 10^{-6}$, where statistical and systematic uncertainties have been combined. The result can be interpreted as a 90% confidence level (CL) upper limit of $26 \times 10^{-6}$. We also find one $B^0$ candidate, with an expected background of $0.64\pm 0.17$ events, implying a 90% CL upper limit of $1.9 \times 10^{-6}$.

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arXiv2003

Branching Fractions in B -> phi h and Search for Direct CP Violation in B+- -> phi K+-

We present preliminary measurements of branching fractions of the b -> s\bar{s}s penguin-dominated decays B+ -> phi K+ and B0 -> phi K0 in a sample of approximately 89 million BBbar pairs collected by the BaBar detector at the PEP-II asymmetric-energy B-meson Factory at SLAC. We determine BF(B+ -> phi K+) = (10.0^{+0.9}_{-0.8} (stat.) \pm 0.5 (syst.)) * 10^{-6} and BF(B^0 -> phi K0) = (7.6^{+1.3}_{-1.2} (stat.) \pm 0.5 (syst.)) * 10^{-6}. Additionally, we measure the charge asymmetry A_{CP}(B+ -> phi K+) = 0.039 \pm 0.086 (stat.) \pm 0.011 (syst.) and set an upper limit on the CKM- and color-suppressed decay B+ -> phi pi+, BF(B+ -> phi pi+) < 0.41 * 10^{-6} (90% CL).

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arXiv2003

Observation of the Decay $B^{\pm} \to π^{\pm}π^{0}$, Study of $B^{\pm} \to K^{\pm}π^{0}$, and Search for $B^{0} \to π^{0}π^{0}$

We present results for the branching fractions and charge asymmetries in $B^{\pm} \to h^{\pm} π^{0}$ (where $h^{\pm} = π^{\pm}, K^{\pm}$) and a search for the decay $B^{0} \to π^{0} π^{0}$ using a sample of approximately 88 million $B\bar{B}$ pairs collected by the BABAR detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. We measure ${\cal B} (B^{\pm} \to π^{\pm} π^{0}) = (5.5 ^{+1.0}_{-0.9} \pm 0.6) \times 10^{-6}$, where the first error is statistical and the second is systematic. The $B^{\pm} \to π^{\pm} π^{0}$ signal has a significance of $7.7 σ$ including systematic uncertainties. We simultaneously measure the $K^{\pm}π^{0}$ branching fraction to be $ {\cal B} (B^{\pm} \to K^{\pm} π^{0}) = (12.8 ^{+1.2}_{-1.1} \pm 1.0) \times 10^{-6}$. The charge asymmetries are ${\cal A}_{π^{\pm}π^{0}} = -0.03_{-0.17}^{+0.18} \pm 0.02$ and ${\cal A}_{K^{\pm}π^{0}} = -0.09 \pm 0.09 \pm 0.01$. We place a 90% confidence-level upper limit on the branching fraction ${\cal B} (B^{0} \to π^{0} π^{0})$ of $3.6 \times 10^{-6} $.

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arXiv2003

Measurement of B0->D_s()+D- Branching Fractions and B0->D_s+D- Polarization with a Partial Reconstruction Technique

We present a study of the decays B0->D_s(*)+D*-, using 20.8 fb-1 of e+e- annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstruction technique, in which only the D_s(*)+ and the soft pion from the D*- decay are reconstructed. We measure the branching fractions BR(B0->D_s+D*-) = (1.03 +/- 0.14 +/- 0.13 +/- 0.26)% and BR(B0->D_s*+D*-) = (1.97 +/- 0.15 +/- 0.30 +/- 0.49)%, where the first error is statistical, the second is systematic, and the third is the error due to the D_s+->phi pi+ branching fraction uncertainty. From the B0->D_s*+D*- angular distributions, we measure the fraction of longitudinal polarization Gamma_L/Gamma = (51.9 +/- 5.0 +/- 2.8)%, which is consistent with theoretical predictions based on factorization.

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arXiv2003

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

We present measurements of branching fractions and CP-violating asymmetries for neutral B meson decays to two-body final states of charged pions and kaons based on a sample of about 88 million Y(4S)-->BB decays. From a time-independent fit we measure the charge-averaged branching fractions B(B0-->pi+pi-) = (4.7 +/- 0.6 +/- 0.2) x 10^-6, B(B0-->K+pi-) = (17.9 +/- 0.9 +/- 0.7) x 10^-6, and the direct CP-violating charge asymmetry A(Kpi) = -0.102 +/- 0.050 +/- 0.016; [-0.188,-0.016], where the ranges in square brackets indicate the 90% confidence intervals. From a time-dependent fit we measure the B0-->pi+pi- CP-violating parameters Spipi = 0.02 +/- 0.34 +/- 0.05; [-0.54,+0.58] and Cpipi = -0.30 +/- 0.25 +/- 0.04; [-0.72,+0.12].

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arXiv2003

Study of Inclusive Production of Charmonium Mesons in B Decay

The inclusive production of charmonium mesons in B meson decay has been studied in a 20.3 fb$^{-1}$ data set collected by the BaBar experiment operating at the $Υ(4S)$ resonance. Branching fractions have been measured for the inclusive production of the charmonium mesons $J/ψ$, $ψ(2S)$, $χ_{c1}$, and $χ_{c2}$. The branching fractions are also presented as a function of the center-of-mass momentum of the mesons and of the helicity of the $J/ψ$.

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arXiv2003

Measurement of $J/ψ$ production in continuum $e^+e^-$ annihilations near $\sqrt s = 10.6$ GeV

The production of $J/ψ$ mesons in continuum $e^+e^-$ annihilations has been studied with the BABAR detector at energies near the $Υ(4S)$ resonance, approximately 10.6 GeV. The mesons are distinguished from $J/ψ$ production in B decays through their center-of-mass momentum and energy. We measure the cross section $e^+e^-\to J/ψX$ to be $2.52\pm 0.21\pm 0.21$ pb; for momentum above 2 GeV/c, it is $1.87\pm 0.10\pm 0.15$ pb. We set a 90% confidence level upper limit on the branching fraction for direct $Υ(4S)$\to J/ψX$ decays at $4.7\times 10^{-4}$.

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arXiv2002

Measurement of the B0 meson lifetime with partial reconstruction of B0 --> D- pi+ and B0 --> D- rho+ decays

The neutral $B$ meson lifetime is measured with the data collected by the BaBar detector at the PEP-II storage ring during the years 1999 and 2000, with a total integrated luminosity of 20.7 ${\rm fb}^{-1}$. The decays $B^0 \to D^{*-} π^+$ and $B^0 \to D^{*-} ρ^+$ are selected with a partial-reconstruction technique, yielding samples of $6970 \pm 240$ and $5520 \pm 250$ signal events, respectively. With these events, the $B^0 $ lifetime is measured to be $ 1.533 \pm 0.034 {\rm (stat.)} \pm 0.038 {\rm (syst.)} {\rm ps}$. This measurement serves as a test and validation of procedures required to measure the CP violation parameter $\sin(2β+ γ)$ with partial reconstruction of these modes.

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arXiv2002

A Study of the Rare Decays $B^0\to D_s^{()+} π^-$ and $B^0\to D_s^{()-} K^+$

We report evidence for the decays $B^0\to D_s^{+} π^-$ and $B^0\to D_s^{-} K^+$ and the results of a search for $B^0 \to D_s^{*+} π^-$ and $B^0\to D_s^{*-} K^+$ in a sample of 84 milion Y(4S) decays into $B\bar{B}$ pairs collected with the BaBar detector at the PEP II asymmetric-energy $e^{+}e^{-}$ storage ring. We measure the branching fraction Br($B^0 \to D_s^{+} π^-) = 3.2 \pm 0.9 ({\rm stat.})\pm 1.0 ({\rm syst.})$. and Br($B^0 \to D_s^{+} π^-) = 3.2 \pm 1.0 ({\rm stat.})\pm 1.0 ({\rm syst.})$. We also set 90% C.L. limits BR($B^0 \to D_s^{*+} π^-) < 4.1\times 10^{-5}$ at 90% C.L and BR($B^0 \to D_s^{*-} K^+)< 2.5\times 10^{-5}$ at 90% C.L.

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arXiv2002

Measurement of Branching Ratios and CP Asymmetries in B- -> D0(CP)K- Decays

We present preliminary results of the analysis of B -> D0 h decays, with h = pi, K and the D0 reconstructed in the channels K- pi+, K- pi+ pi+ pi-, K- pi+ pi0 and in the CP eigenstate K-K+, using data collected by the BABAR detector during the years 2000-2002 at the PEP-II asymmetric-energy B Factory at SLAC. We have measured the ratio of the branching fractions R = Br(B- -> D0 K-) / Br(B- -> D0 pi-) = (8.31 +- 0.35 (stat) +- 0.20 (syst))% and the direct CP asymmetry A(CP) = (Br(B- -> D0(CP) K-) - Br(B+ -> D0(CP) K+)) / (Br(B- -> D0(CP) K-)+Br(B+ -> D0(CP) K+)) = 0.17 +- 0.23 (stat) +0.09 -0.07 (syst).

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arXiv2002

Dalitz Plot Analysis of D0 Hadronic Decays D0 -> K0K-pi+, D0 -> K0barK+pi- and D0 -> K0barK+K-

A Dalitz plot analysis of the D0 hadronic decays D0 -> K0 K- pi+, D0 -> K0bar K+ pi- and D0 -> K0bar K+ K- is presented. This analysis is based on a data sample of 22 fb-1 collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC running on or near the Y(4S) resonance. The events are selected from continuum e+ e- annihilations using the decay D*+ -> D0 pi+. Preliminary measurements of the branching fractions of the above hadronic decays are obtained. Preliminary estimates of fractions and phases for resonant and nonresonant contributions to the Dalitz plot are also presented.

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