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The BABAR Collaboration

Publications and source records attributed to The BABAR Collaboration.

At least 469 records · Page 26Linked to original sources

arXiv2004

Measurement of CP-violating parameters in fully reconstructed $B\to D^{(*)}π$ and $B\to Dρ$ decays

We present a preliminary measurement of CP-violating asymmetries in fully reconstructed $B^0{\to}D^{(*)\pm}π^{\mp}$ and $\B^0{\to}D^{\pm}ρ^{\mp}$ decays in approximately 110 million $Υ(\rm 4S) \to B\bar{B}$ decays collected with the BaBar detector at the PEP-II asymmetric-energy $B$ factory at SLAC. % From a maximum likelihood fit to the time-dependent decay distributions we obtain for the CP-violating parameters: $a^{Dπ} = -0.032\pm0.031 (\textrm{stat.})\pm 0.020 (\textrm{syst.}), c_{\rm lep}^{Dπ} = -0.059\pm0.055 (\textrm{stat.})\pm 0.033 (\textrm{syst.})$ on the $B^0{\to}D^{\pm}π^{\mp}$ sample, $a^{D^*π} = -0.049\pm0.031 (\textrm{stat.})\pm 0.020 (\textrm{syst.}), c_{\rm lep}^{D^*π} = +0.044\pm0.054 (\textrm{stat.})\pm 0.033 (\textrm{syst.})$ on the $B^0{\to}D^{*\pm}π^{\mp}$ sample, and $a^{Dρ} = -0.005\pm0.044 (\textrm{stat.})\pm 0.021 (\textrm{syst.}), c_{\rm lep}^{Dρ} = -0.147\pm0.074 (\textrm{stat.})\pm 0.035 (\textrm{syst.})$ on the $B^0{\to}D^{\pm}ρ^{\mp}$ sample.

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arXiv2004

Measurement of the Ratio BR(B- --> D0 K-)/BR(B- --> D0 pi-) and the CP-asymmetry of B- --> D*0(CP+) K- decays with the BABAR detector

We present a study of the decays B- --> D*0 pi- and B- --> D*0 K-, where the D*0 decays into D0 pi0, with the D0 reconstructed in the CP eigenstates K- K+ and pi- pi+ and in the (non-CP) channels K- pi+, K- pi+ pi+ pi-, and K- pi+ pi0. We use an unbinned maximum likelihood fit to measure the signal yields. Using a sample of about 123 million Y(4S) decays into B anti-B pairs, we measure the ratios of decay rates R*(CP+)=BR(B- --> D*0(CP+) K-)/BR(B- --> D*0(CP+) pi-) = 0.088+-0.021(stat)+0.007-0.005(syst), and provide the first measurements of R*(non-CP) = BR(B- --> D*0(non-CP) K-)/BR(B- --> D*0(non-CP) pi-) = 0.0805+-0.0040(stat)+0.0039-0.0032(syst), and of the CP asymmetry A*(CP+) = (BR(B- --> D*0(CP+) K-)-BR(B+ --> D*0(CP+) K+))/(BR(B- --> D*0(CP+) K-)+BR(B+ --> D*0(CP+) K+)) = -0.02+-0.24(stat)\+-0.05(syst). These results are preliminary.

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arXiv2004

Measurements of the Branching Fraction and CP-Violating Asymmetries of B0 --> K0S Pi0 Decays

We present measurements of the branching fraction and time-dependent CP-violating (CPV) asymmetries in B0 --> K0S Pi0 decays based on 227 million Y(4S) --> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy B factory at SLAC. We obtain a branching fraction B(B0 --> K0 Pi0) = (11.4 +/- 0.9 +/- 0.6) x 10^{-6}, the magnitude of the direct CPV asymmetry C = 0.06 +/- 0.18 +/- 0.06 and the magnitude of the CPV asymmetry in the interference between mixing and decay S = 0.35 +0.30/-0.33 +/- 0.04, where the first error is statistical and the second systematic. All results are preliminary.

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arXiv2004

Search for the Decay B0->K*+rho-

We present the preliminary result of a search for the decay of $B^0\to K^{*+}ρ^-$. The data were recorded with the $BaBar$ detector at the PEPII collider and correspond to 123 million $B\bar{B}$ pairs produced in the $e^+e^-$ annihilation through the $Υ(4S)$ resonance. We obtain an upper limit on the branching fraction for this decay of ${\cal B}(B^0\to K^{*+}ρ^-) <24 \times 10^{-6}$ (90% C.L.). All results are preliminary.

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arXiv2004

Searches for Charmless Decays B0 -> eta omega, B0 -> eta K0, B+ -> eta rho+, and B+ -> eta' pi+

We present measurements of branching fractions for four previously unobserved B-meson decays with an eta or eta' meson in the final state. The data sample corresponds to 182 million B-Bbar pairs produced from e+e- annihilation at the Upsilon(4S) resonance. We measure the following branching fractions in units of 10^-6: BF(B0 -> eta omega) = 1.2 +/- 0.6 +/- 0.2 (<2.3 at 90% C.L.), BF(B0 -> eta K0) = 2.5 +/-0.8 +/- 0.1, BF(B+ -> eta rho+) = 8.6 +/- 2.2 +/- 1.1, and BF(B+ -> eta' pi+) = 4.2 +/- 1.0 +/- 0.5, where the first error quoted is statistical and the second systematic. The charge asymmetries are A_ch(B+ -> eta rho+) = (7 +/- 19 +/- 2)% and A_ch(B+ -> eta' pi+) = (24 +/- 19 +/- 1)%. All results are preliminary.

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arXiv2004

Measurement of the B -> Xs l+ l- branching fraction with a sum over exclusive modes

We measure the branching fraction for the flavor-changing neutral-current process B -> Xs l+ l- with a sample of 89 x 10^6 Upsilon(4S) -> BBbar events recorded with the BaBar detector at the PEP-II e+e- storage ring. The final state is reconstructed from e+e- or mu+mu- pairs and a hadronic system consisting of one K or K0s and up to two pions, with at most one pi0. We observe a signal of 40 +/- 10(stat) +/- 2(syst) events and extract the inclusive branching fraction B(B -> Xs l+ l-) = (5.6 +/- 1.5(stat) +/- 0.6(exp syst) +/- 1.1(model syst)) x 10^-6 for mll > 0.2 GeV/c^2.

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arXiv2004

A Search for the Rare Decay B0 --> D_S+ rho-

We report on a search for the decay B0 --> D_S+ rho- in a sample of 90 million Y(4S) decays into B meson pairs collected between 1999 and 2001 with the BaBar detector at the PEP-II asymmetric-energy e+e- collider. No significant excess of signal events above the expected background is observed. We set a 90% C.L. limit on the branching fraction Br(B0 --> D_S+ rho-)< 1.9*10^{-5}. Assuming a flavor SU(3) symmetry relation between the decays B0 --> D_S+ rho- and B0 --> D+ rho-, we set a limit on the ratio of CKM-suppressed to CKM-favored amplitudes r(D rho)<9.5*10^{-3} at 90% C.L. All results are preliminary.

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arXiv2004

Measurement of the Branching Fractions for the Decays B0->D^{-} ppbar pi^+, B0->D^-ppbar pi^+, B0->D^{0} ppbar and B0->D^0 ppbar

The $B^0$ meson decay modes $B^0 \to D^{*-} p {\bar p} π^+$, $D^{-} p {\bar p} π^+$, ${\bar D}^{*0} p {\bar p}$, and ${\bar D}^{0} p {\bar p}$ are studied in a sample of $124\times 10^{6}$ $B{\bar B}$ pairs collected with the $BaBar$ detector at the PEP-II collider. The decay of $B^0 \to D^{-} p {\bar p} π^+$ is observed for the first time, with a measured branching fraction ${\cal B}(B^0 \to D^{-} p {\bar p} π^+)=(3.80\pm 0.35\pm 0.46)\times 10^{-4}$. The following branching fractions are also determined: ${\cal B}(B^0 \to D^{*-} p {\bar p} π^+)= (5.61\pm 0.59\pm 0.73)\times 10^{-4}$, ${\cal B}(B^0 \to {\bar D}^{*0} p {\bar p})= (0.67\pm 0.21\pm 0.09)\times 10^{-4}$, and ${\cal B}(B^0 \to {\bar D}^{0} p {\bar p})= (1.24\pm 0.14\pm 0.12)\times 10^{-4}$. In each decay mode the invariant mass spectra of the charmed mesons and the baryons are compared with a pure phase-space hypothesis in order to gain insight into the $B$ meson decay dynamics. In particular, the Dalitz plots of ${\bar D}^{*0} p$ versus ${\bar D}^{*0} {\bar p}$ for $B^0 \to {\bar D}^{*0} p {\bar p}$ and of ${\bar D}^{0} p$ versus ${\bar D}^{0} {\bar p}$ for $B^0 \to {\bar D}^{0} p {\bar p}$ are presented. All results are preliminary.

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arXiv2004

Measurement of Time-Dependent CP Asymmetries and Constraints on sin(2 beta+gamma) with Partial Reconstruction of B0->D*-+ pi+- Decays

We present a preliminary measurement of the time-dependent CP-violating asymmetry in decays of neutral B mesons to the final states D*-+ pi+- using approximately 178 million BB events recorded by the BaBar experiment at the PEP-II e+e- storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high-momentum pi+- from the B decay and the low-momentum pi-+ from the D*-+ decay are used. % We measure the amplitude of the asymmetry to be $-0.041 \pm 0.016 (stat.) \pm 0.010 (syst.)$ and determine bounds on $|\sin(2 β+ γ)|$.

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arXiv2004

Measurement of the Branching Fraction of e^+e^- --> B0B0bar at the Upsilon(4S) Resonance

We report a measurement of the branching fraction e^+e^- --> B0B0bar with a data sample of 81.7 fb^-1 collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy e^+e^- storage ring. Using partial reconstruction of the decay B0bar --> D^{*+} \ell^{-} \barν_{\ell} we obtain a preliminary result of f00 = 0.486 +- 0.010(stat.) +- 0.009(sys.). Our result does not depend on branching fractions of the B0bar and the D^{*+} decay chains, on the simulated reconstruction efficiency, on the ratio of the charged and neutral B meson lifetimes, nor on assumption of isospin symmetry. This measurement is important for normalizing many B decay branching fractions, and contributes to our understanding of isospin violation in the Upsilon(4S) system.

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arXiv2004

Measurement of the B0->PhiK*0 Decay Amplitudes

With a sample of about 227 million BB pairs recorded with the BABAR detector at the PEP-II storage ring we perform a full angular analysis of the decay B0->PhiK*0(892). We measure the branching fraction to be (9.2+-0.9+-0.5)10^-6 and determine the fractions of longitudinal and parity-odd transverse contributions as f_L=0.52+-0.05+-0.02 and f_perp=0.22+-0.05+-0.02, respectively. The phases of the parity-even and parity-odd transverse amplitudes relative to the longitudinal amplitude are found to be phi_parallel= 2.34+0.23-0.20+-0.05 rad and phi_perp=2.47+-0.25+-0.05 rad, respectively. We measure five CP asymmetries which provide important limits on CP violation originating from new physics. We also observe the decay B0->PhiK*0(1430).

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arXiv2004

Branching Fractions and CP Asymmetries in B0 --> K+ K- K0S and B+ --> K+ K0S K0S

We measure the branching fractions and CP asymmetries in the decays B0 --> K+K-K0S and B+ --> K+K0S K0S using a sample of approximately 122 million BBbar pairs collected by the BaBar detector. From a time-dependent analysis of the K+ K- K0S sample that excludes phi K0S, the values of the CP-violation parameters are S = -0.56 +/- 0.25 +/- 0.04 and C = -0.10 +/- 0.19 +/- 0.10, where the first uncertainty is statistical, the second is systematic. We confirm that the final state is nearly purely CP-even. Using this result and setting C=0, we extract the Standard Model parameter sin2beta = 0.57 +/- 0.26 +/- 0.04 +0.17/-0 where the last error is due to uncertainty on the CP content. We present the first measurement of the CP-violating charge asymmetry ACP(B+ --> K+K0S K0S) = -0.04 +/- 0.11 +/- 0.02, with a 90% confidence-level interval of [-0.23, 0.15]. The branching fractions are BF(B0 --> K+K-K0) = (23.8 +/- 2.0 +/- 1.6) x 10^{-6} and BF(B+ --> K+K0S K0S) = (10.7 +/- 1.2 +/- 1.0) x 10^{-6}.

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arXiv2004

B Meson Decays to eta(')K*, eta(')rho,eta(')pi0, omegapi0, and phipi0

We present measurements of the branching fractions and charge asymmetries (where appropriate) of two-body B decays to eta(')K*, eta(')rho, eta(')pi0, omegapi0, and phipi0. The data were recorded with the BABAR detector at PEP-II and correspond to 89x10^6 BB pairs produced in e+e- annihilation through the Upsilon(4S) resonance. We find significant signals for two decay modes and measure the branching fractions BR(B+->etaK*+)=(25.6+/-4.0+/-2.4)x10^{-6} and BR(B0->etaK*0)=(18.6+/-2.3+/-1.2)x10^{-6}, where the first error is statistical and the second systematic. We also find evidence with significance 3.5sigma for a third decay mode and measure BR(B+->etarho+)= (9.2+/-3.4+/-1.0)x10^{-6}. For other channels, we set 90% C.L. upper limits of BR(B0->etarho0)<1.5x10^{-6}, BR(B+->eta'K*+) < 14x10^{-6}, BR(B0->eta'K*0) < 7.6x10^{-6}, BR(B+->eta'rho+) < 22x10^{-6}, BR(B0->eta'rho0) < 4.3x10^{-6}, BR(B0->etapi0) < 2.5x10^{-6}, BR(B0->eta'pi0) < 3.7x10^{-6}, BR(B0->omegapi0) < 1.2x10^{-6}, and BR(B0->phipi0) < 1.0x10^{-6}. For self-flavor-tagging modes with significant signals, the time-integrated charge asymmetries are A_ch(B+->etaK*+)=+0.13\pm0.14\pm0.02 and A_ch(B0->etaK*0)=+0.02\pm0.11\pm0.02.

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arXiv2004

Searches for B0 Decays to Combinations of Charmless Isoscalar Mesons

We search for B meson decays into two-body combinations of eta, eta', omega, and phi mesons from 89 million B B-bar pairs collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find the branching fraction BF(B0 -> eta omega) = (4.0^{+1.3}_{-1.2} +- 0.4) x 10^-6 with a significance of 4.3 sigma. For all the other decay modes we set the following 90% confidence level upper limits on the branching fractions, in units of 10^-6 : BF(B0 -> eta eta)<2.8, BF(B0 -> eta eta')<4.6, BF(B0 -> eta' eta')<10, BF(B0 -> eta'omega)<2.8, BF(B0 -> eta phi)<1.0, BF(B0 -> eta' phi)<4.5, BF(B0 -> phi phi)<1.5.

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arXiv2004

Branching Fraction Measurements of B ->etac K Decays

We study the decays B+ -> etac K+ and B0 -> etac K0, where the etac is reconstructed in the Ks K+ pi- and K+ K- pi0 decay modes. Results are based on a sample of 86 million BBbar pairs collected with the BaBar detector at the SLAC e+e- B Factory. We measure the branching fractions BR(B+ -> etac K+) = (1.34 +/- 0.09 +/- 0.13 +/- 0.41) x 10^{-3} and BR(B0 -> etac K0) = (1.18 +/- 0.16 +/- 0.13 +/- 0.37) x 10^{-3}, where the first error is statistical, the second is systematic, and the third reflects the etac branching fraction uncertainty. In addition, we search for B -> etac K events with etac -> 2(K+K-) and etac -> phi phi and determine the etac decay branching fraction ratios BR(etac -> 2(K+K-))/BR(etac -> K Kbar pi) = (2.3 +/- 0.7 +/- 0.6) x 10^{-2} and BR(etac -> phi phi)/BR(etac -> K Kbar pi) = (5.5 +/- 1.4 +/- 0.5) x 10^{-2}.

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arXiv2004

Measurements of CP-violating Asymmetries in $B^{0}\to K_{s}^{0}π^{0}$ Decays

We present a measurement of the time-dependent CP-violating (CPV) asymmetries in $B^{0}\to K_{s}^{0}π^{0}$ decays based on 124 million $Υ(4S)\to B\bar{B}$ decays collected with the BaBar detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. In a sample containing $122\pm 16$ signal decays, we obtain the magnitude of the direct CPV asymmetry $C_{K_{s}^{0}π^{0}} = 0.40^{+0.27}_{-0.28} \pm 0.09$ and the magnitude of the CPV asymmetry in the interference between mixing and decay $S_{K_{s}^{0}π^{0}} = 0.48^{+0.38}_{-0.47} \pm 0.06$ where the first error is statistical and the second systematic.

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arXiv2004

Measurements of branching fractions in B -> phi K and B -> phi pi and search for direct CP violation in B+/- -> phi K+/-

We present measurements of branching fractions in the b -> s s-bar 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 B(B+ --> phi K+) = (10.0 +0.9 -0.8 +/- 0.5) x 10^{-6} and B(B0 --> phi K0) = (8.4 +1.5 -1.3 +/- 0.5) x 10^{-6}. Additionally, we measure the CP-violating charge asymmetry ACP (B+/- --> phi K+/-) = 0.04 +/- 0.09 +/- 0.01, with a 90% confidence interval of [-0.10, 0.18], and set an upper limit B(B+ --> phi pi+) < 0.41 x 10^{-6} (at the 90% confidence level).

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arXiv2004

Study of B^+/- --> J/psi pi^+/- and B^+/- --> J/psi K^+/- Decays: Measurement of the Ratio of Branching Fractions and Search for Direct CP Violation

We study B^+/- --> J/psi pi^+/- and B^+/- --> J/psi K^+/- decays in a sample of about 89 million BB~ pairs collected with the BABAR detector at the PEP-II asymmetric B-factory at SLAC. We observe a signal of 244 +/- 20 B^+/- --> J/psi pi^+/- events and determine the ratio BF(B^+/- --> J/psi pi^+/-)/BF(B^+/- --> J/psi K^+/-) to be [5.37 +/- 0.45 (stat.) +/- 0.11 (syst)]%. The charge asymmetries for the B^+/- --> J/psi pi^+/- and B^+/- --> J/psi K^+/- decays are determined to be A_pi = 0.123 +/- 0.085 (stat.) +/- 0.004 (syst.) and A_K = 0.030 +/- 0.015 (stat.) +/- 0.006 (syst.), respectively.

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