arXiv subjects

B. Aubert

Publications and source records attributed to B. Aubert.

At least 487 records · Page 27Linked to original sources

arXiv2004

Measurement of the Direct CP Asymmetry in b -> s gamma Decays

We describe a measurement of the direct CP asymmetry between inclusive b -> s gamma and bbar -> sbar gamma decays. This asymmetry is expected to be less than 0.01 in the Standard Model, but could be enhanced up to about 0.10 by new physics contributions. We use a sample of 89 million BB pairs recorded with the BaBar detector at PEP-II, from which we reconstruct a set of 12 exclusive b -> s gamma final states containing one charged or neutral kaon and one to three pions. We measure an asymmetry of A_CP(b -> s gamma) = 0.025 +/- 0.050(stat.) +/- 0.015(syst.), corresponding to an allowed range of -0.06 < A_CP(b -> s gamma) < +0.11 at 90% confidence level.

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arXiv2004

Measurements of Moments of the Hadronic Mass Distribution in Semileptonic B Decays

We report a measurement of the first four moments of the hadronic mass distribution in B --> X_c lv decays. The measurements are based on 89 million Upsilon(4S) --> BBbar events where the hadronic decay of one of the B mesons is fully reconstructed and a charged lepton from the decay of the other B meson is identified. The moments are presented for minimum lepton momenta ranging from 0.9 to 1.6 GeV in the B rest frame. It is expected that such measurements will lead to improved determinations of |V_{cb}| and |V_{ub}|.

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arXiv2004

Measurement of the Time-Dependent CP Asymmetry in the B0 --> Phi K0 Decay

We present a measurement of the time-dependent CP asymmetry for the neutral B-meson decay B0 --> Phi K0. We use a sample of approximately 114 million B-meson pairs taken at the Upsilon(4S) resonance with the BaBar detector at the PEP-II B-meson Factory at SLAC. We reconstruct the CP eigenstates Phi K0_S and Phi K0_L where Phi --> K+ K-, K0_S --> pi+ pi-, and K0_L is observed via its hadronic interactions. The other B meson in the event is tagged as either a B0 or B0-bar from its decay products. The values of the CP-violation parameters are S = 0.47 +/- 0.34 (stat) +0.08/-0.06 (syst) and C = 0.01 +/- 0.33 (stat) +/- 0.10 (syst).

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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

Observation of the Decay B=> J/psi eta K and Search for X(3872)=> J/psi eta

We report the observation of the $B$ meson decay $B^\pm\to J/ψηK^\pm$ and evidence for the decay $B^0\to J/ψηK^0_S$, using {90} million $BBbar$ events collected at the $\ensuremath{Υ{(4S)}}\xspace$ resonance with the $BaBar$ detector at the PEP-II $e^+ e^-$ asymmetric-energy storage ring. We obtain branching fractions of $\cal{B}$$(B^\pm\to J/ψηK^{\pm}$)=$(10.8\pm 2.3(\rm{stat.})\pm 2.4(\rm{syst.}))\times 10^{-5}$ and $\cal{B}$$(B^0\to J/ψηK_{\rm{S}}^{0}$)=$(8.4\pm 2.6(\rm{stat.})\pm 2.7(\rm{syst.}))\times 10^{-5}$. We search for the new narrow mass state, the X(3872), recently reported by the Belle Collaboration, in the decay $B^\pm\to X(3872)K^\pm, X(3872)\to \jpsi η$ and determine an upper limit of $\cal{B}$$(B^\pm \to X(3872) K^\pm \to \jpsi ηK^\pm$) $<7.7\times 10^{-6}$ at 90% C.L.

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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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arXiv2004

Observation of a Narrow Meson Decaying to Ds pi0 gamma at a Mass of 2.458 GeV/c^2

A narrow state, which we label DsJ(2458)+, with mass 2458.0 +/- 1.0(stat.) +/- 1.0(syst.) MeV/c^2, is observed in the inclusive Ds+ pi0 γ$ mass distribution in 91 fb-1 of e^+e^- annihilation data recorded by the BABAR detector at the PEP-II asymmetric-energy e^+e^- storage ring. The observed width is consistent with the experimental resolution. The data favor decay through Ds*(2112)+ pi0 rather than through DsJ*(2317)+ gamma. An analysis of Ds+ pi0 data accounting for the influence of the DsJ(2458)+ produces a DsJ*(2317)+ mass of 2317.3 +/- 0.4(stat.) +/- 0.8(syst.) MeV/c^2.

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arXiv2004

Measurement of the B^+/B^0 Production Ratio from the Upsilon(4S) Meson using B^+ -> J/psi K^+ and B^0 -> J/psi K^{0}_{S} Decays

We report a measurement of the production ratio of charged and neutral B mesons from Upsilon(4S) decays based on the ratio of efficiency-corrected yields for the charmonium modes J/psi K^+ and J/psi K^{0}_{S} with 81.9 fb^-1 of data collected with the BABAR detector on the Upsilon(4S) resonance at 10.580 GeV. We find a value of 1.006 +/- 0.036 (stat) +/- 0.031 (sys) for the ratio R^{+/0}=Gamma(Upsilon(4S) -> B^+ B^-)/Gamma(Upsilon(4S)->B^0 B^0bar).

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arXiv2004

Study of high momentum eta' production in B -> eta' X_s

We measure the branching fraction for the charmless semi-inclusive process B -> eta' X_s, where the eta' meson has a momentum in the range 2.0 to 2.7 GeV/c in the Upsilon(4S) center-of-mass frame and X_s represents a system comprising a kaon and zero to four pions. We find B(B -> eta' X_s)=(3.9+/-0.8(stat)+/-0.5(syst)+/-0.8(model)).10^{-4}. We also obtain the X_s mass distribution and find that it tends to favor models predicting high masses.

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arXiv2004

Search for the Rare Leptonic Decay B+ --> mu+ nu_mu

We have performed a search for the rare leptonic decay B+ --> mu+ nu_mu with data collected at the Upsilon(4S) resonance by the BABAR experiment at the PEP-II storage ring. In a sample of 88.4 million BBbar pairs, we find no significant evidence for a signal and set an upper limit on the branching fraction BR(B+ --> mu+ nu_mu) < 6.6 x 10^{-6} at the 90% confidence level.

hep-ex↗

arXiv2003

Measurements of Branching Fractions and CP-Violating Asymmetries in B Meson Decays to Charmless Two-Body States Containing a K0

We present measurements of branching fractions and \CP-violating asymmetries in decays of $B$ mesons to two-body final states containing a \Kz. The results are based on a data sample of approximately 88 million \upsbb decays collected with the \babar detector at the \pep2 asymmetric-energy $B$ Factory at SLAC. We measure $\BR(\Bp\to\Kz\pip) = (22.3 \pm 1.7 \pm 1.1)\times 10^{-6}$, $\BR(\Bz\to\Kz\piz) = (11.4\pm 1.7\pm 0.8)\times 10^{-6}$, $\BR(\Bp\to\Kzb\Kp) < 2.5\times 10^{-6}$, and $\BR(\Bz\to\KzKzb) < 1.8\times 10^{-6}$, where the first uncertainty is statistical and the second is systematic, and the upper limits are at the 90% confidence level. In addition, the following \CP-violating asymmetries have been measured: ${\cal A}_{CP}(\Bp\to\Kz\pip) = -0.05 \pm 0.08 \pm 0.01$ and ${\cal A}_{CP}(\Bz\to\Kz\piz) = 0.03 \pm 0.36\pm 0.11$.

hep-ex↗

arXiv2003

Measurement of the Branching Fraction for B- --> D0 K*-

We present a measurement of the branching fraction for the decay B- --> D0 K*- using a sample of approximately 86 million BBbar pairs collected by the BaBar detector from e+e- collisions near the Y(4S) resonance. The D0 is detected through its decays to K- pi+, K- pi+ pi0 and K- pi+ pi- pi+, and the K*- through its decay to K0S pi-. We measure the branching fraction to be B.F.(B- --> D0 K*-)= (6.3 +/- 0.7(stat.) +/- 0.5(syst.)) x 10^{-4}.

hep-ex↗

arXiv2003

Search for Lepton-Flavor Violation in the Decay $τ^-\to\ell^-\ell^+\ell^-$

A search for the lepton-flavor-violating decay of the tau into three charged leptons has been performed using $91.5 \mathrm{fb}^{-1}$ of data collected at an $e^+e^-$ center-of-mass energy of 10.58 GeV with the BaBar detector at the PEP-II storage ring. In all six decay modes considered, the numbers of events found in data are compatible with the background expectations. Upper limits on the branching fractions are set in the range $(1-3) \times 10^{-7}$ at 90% confidence level.

hep-ex↗

arXiv2003

Measurement of Branching Fractions and Charge Asymmetries in B+ --> rho+pi0 and B+ -->rho0pi+ Decays, and Search for B0 --> rho0pi0

We present measurements of branching fractions and charge asymmetries in $B$-meson decays to $ρ^+ π^{0}$, $ρ^{0}π^+$ and $ρ^0π^0$. The data sample comprises $89 \times 10^6$ $Υ(4S) \to B\bar{B}$ decays collected with the $BaBar$ detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. We find the charge-averaged branching fractions ${\cal B}(B^{+}\to ρ^{+}π^0) = (10.9 \pm 1.9{\rm (stat)} \pm 1.9{\rm (syst)})\times 10^{-6}$ and ${\cal B}(B^{+} \to ρ^0 π^{+}) = (9.5 \pm 1.1{\rm (stat)} \pm 0.8{\rm (syst)}) \times 10^{-6}$, and we set a 90% confidence-level upper limit ${\cal B}(B^0 \to ρ^0π^0) < 2.9 \times 10^{-6}$. We measure the charge asymmetries $A_{CP}^{ρ^{+}π^0} = 0.24 \pm 0.16 \pm 0.06$ and $A_{CP}^{ρ^0π^{+}} = -0.19 \pm 0.11 \pm 0.02$.

hep-ex↗

arXiv2003

Measurements of the mass and width of the eta_c meson and of an eta_c(2S) candidate

The mass and total width of the eta_c meson have been measured in two-photon interactions at the SLAC asymmetric B-Factory with the BABAR detector. With a sample of approximately 2500 reconstructed eta_c -> Ks K pi decays in 88 fb-1 of data, the measured eta_c mass and width are respectively 2982.5 +- 1.1 (stat) +- 0.9 (syst) MeV/c2 and 34.3 +- 2.3 (stat) +- 0.9 (syst) MeV/c2. Using the same decay mode, a second resonance with 112 +- 24 events is observed with a mass of 3630.8 +- 3.4 (stat) +- 1.0 (syst) MeV/c2 and width of 17.0 +- 8.3 (stat) +- 2.5 (syst) MeV/c2. This observation is consistent with expectations for the eta_c(2S) state.

hep-ex↗

arXiv2003

Measurement of the branching fractions and CP-asymmetry of B^- -> D^0_(CP) K^- decays with the BaBar detector

We present a study of B- -> D^0_CP K^- decays, where D^0_CP is reconstructed in CP-even channels, based on a sample of 88.8 million Upsilon(4S)->BBbar decays collected with the BaBar detector at the PEP-II e^+e^- storage ring. We measure the ratio of Cabibbo-suppressed to Cabibbo-favored branching fractions Br(B- -> D^0_CP K^-)/Br(B- -> D^0_CP pi^-)= (8.8 +/- 1.6(stat) +/- 0.5(syst))\times 10^{-2} and the CP asymmetry A_CP= 0.07 +/- 0.17(stat) +/- 0.06(syst). We also measure Br(B- ->D0K-)/Br(B- ->D0pi-)=(8.31 +/- 0.35(stat) +/- 0.20(syst))\times 10^{-2} using a sample of 61.0 million BBbar pairs.

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