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B. Aubert

Publications and source records attributed to B. Aubert.

At least 505 records · Page 28Linked to original sources
arXiv2003

Observation of the Decay B0 => rho+ rho- and Measurement of the Branching Fraction and Polarization

We have observed the rare decay B0 => rho+ rho- in a sample of 89 million BB pairs recorded with the BABAR detector. The number of observed events is 88 +23-21 +-9, with a significance of 5.1 standard deviations with systematic uncertainties included. The branching fraction and the longitudinal polarization are measured to be BR(B0 => rho+ rho-) = (25 +7-6 +5-6)*10^{-6} and Gamma_L/Gamma = 0.98 +0.02-0.08 +-0.03, respectively.

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arXiv2003

Observation of $B^0\raωK^0$, $B^+\raηπ^+$, and $B^+\raηK^+$ and Study of Related Decays

We present measurements of branching fractions and charge asymmetries for seven B-meson decays with an eta, eta' or omega meson in the final state. The data sample corresponds to 89 million BBbar pairs produced from e+e- annihilation at the Upsilon(4S) resonance. We measure the following branching fractions in units of 10^{-6}: B(etapi+)=5.3+/-1.0+/-0.3, B(etaK+)=3.4+/-0.8+/-0.2, B(etaK0)=2.9+/-1.0+/- 0.2 (<5.2, 90% C.L.), B(eta'pi+=2.7+/-1.2+/-0.3 (<4.5, 90% C.L.), B(omegapi+)=5.5+/-0.9+/-0.5, B(omegaKp)=4.8+/-0.8+/-0.4, and B(omegaK0)=5.9+1.6-1.3+/-0.5. The charge asymmetries are A_ch(etapi+)=-0.44+/-0.18+/-0.01, A_ch(etaK+)=-0.52+/-0.24+/-0.01, A_ch(omegapi+)=0.03+/-0.16+/-0.01 and A_ch(omegaK+)=-0.09+/-0.17+/-0.01.

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arXiv2003

Measurement of sin2beta with Hadronic and Previously Unused Muonic J/psi Decays

We report a measurement of the CP-violation parameter sin2beta with B^0 -> J/psi K^0_S decays in which the J/psi decays to hadrons or to muons that do not satisfy our standard identification criteria. With a sample of 88 million BBbar events collected by the BaBar detector at the PEP-II asymmetric-energy $B$ factory at SLAC, we reconstruct 100 +/- 17 such events, with J/psi -> pi^+ pi^- pi^0 being the most prevalent, and measure sin2beta = 1.56 +/- 0.42 (stat.) +/- 0.21 (syst.).

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arXiv2003

Measurement of the Average $ϕ$ Multiplicity in $B$ Meson Decay

We present a measurement of the average multiplicity of $ϕ$ mesons in $B^0$, $\kern 0.18em\bar{\kern -0.18em B}{}^0$ and $B^\pm$ meson decays. Using $17.6 fb^{-1}$ of data taken at the $Υ{(4S)}\xspace$ resonance by the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the PEP-II $e^+e^-\xspace$ storage ring at the Stanford Linear Accelerator Center, we reconstruct $ϕ$ mesons in the $K^+K^-$ decay mode and measure ${\cal{B}}(B\to ϕX) = (3.41\pm0.06\pm0.12)%$. This is significantly more precise than any previous measurement.

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arXiv2003

Rates, Polarizations, and Asymmetries in Charmless Vector-Vector B Meson Decays

With a sample of approximately 89 million BBbar pairs collected with the BABAR detector, we perform a search for B meson decays into pairs of charmless vector mesons (phi, rho, and K*). We measure the branching fractions, determine the degree of longitudinal polarization, and search for CP violation asymmetries in the processes B->phiK*+, B->phiK*0, B->rho0K*+, and B->rho0rho+. We also set an upper limit on the branching fraction for the decay B->rho0rho0.

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arXiv2003

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

We present a measurement of time-dependent CP-violating asymmetries in decays of neutral B mesons to the final states D*-+ pi+-, using approximately 82 million B B bar 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 -0.063 +- 0.024(stat.) +- 0.014(syst.) and compute bounds on |sin(2beta + gamma)|.

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arXiv2003

J/psi production via initial state radiation in e+ e- --> mu+ mu- gamma at an e+e- center-of-mass energy near 10.6 GeV

We have used a study of the process e+e- --> mu+ mu- gamma at a center-of-mass energy near the Y(4S) resonance for a mu+ mu- invariant mass range near the J/psi mass to extract the cross section sigma(e+e- --> J/psi gamma --> mu+ mu- gamma). The data set, corresponding to an integrated luminosity of 88.4 fb-1, was collected using the BaBar detector at the PEP-II collider. We measure the product Gamma(J/psi --> e+e-)B(J/psi --> mu+ mu-) to be 0.330 +/- 0.008(stat) +/- 0.007(syst) keV. Using the world averages for B(J/psi --> mu+ mu-) and B(J/psi --> e+e-), we derive the J/psi electronic and total widths: Gamma(J/psi --> e+e-)=5.61+/-0.20 keV and Gamma=94.7+/-4.4 keV.

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arXiv2003

Measurement of Branching Fractions of Color-Suppressed Decays of the B0bar Meson to D(*)0 pi0, D(*)0 eta, D(*)0 omega, and D0 eta_prime

Using a sample of 88.8 10**6 BBbar events collected with the BaBar detector at the PEP-II storage rings at the Stanford Linear Accelerator Center, we measure the branching fractions of seven color-suppressed B-meson decays: BF(B0bar to D0 pi0)=(2.9 +/- 0.2(stat.)+/- 0.3(syst.))*10**-4, BF(B0bar to D*0 pi0)=(2.9 +/- 0.4(stat.)+/- 0.5(syst.))*10**-4, BF(B0bar to D0 eta)=(2.5 +/- 0.2(stat.)+/- 0.3(syst.))*10**-4, BF(B0bar to D*0 eta)=(2.6 +/- 0.4(stat.)+/- 0.4(syst.))*10**-4, BF(B0bar to D0 omega)=(3.0 +/- 0.3(stat.)+/- 0.4(syst.))*10**-4, BF(B0bar to D*0 omega)=(4.2 +/- 0.7(stat.)+/- 0.9(syst.))*10**-4, and BF(B0bar to D0 eta_prime)=(1.7 +/- 0.4(stat.)+/- 0.2(syst.))*10**-4. We set the 90 % confidence-level upper limit: BF(B0bar to D*0 eta_prime) < 2.6*10**-4. The channels B0bar to D*0 eta, D*0 omega, and D0 eta_prime are seen with more than five-sigma statistical significance. All of these branching fractions are significantly larger than theoretical expectations based on the ``naive'' factorization model.

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arXiv2003

Measurement of the Branching Fraction for B+- --> chi_c0 K+-

We present a measurement of the branching fraction of the decay B+- --> chi_c0 K+- from a sample of 89 million BB pairs collected by the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. The chi_c0 meson is reconstructed through its two-body decays to pi+ pi- and K+ K-. We measure BR(B+- --> chi_c0 K+-)* BR(chi_c0 --> pi+ pi-) = (1.32^{+0.28}_{-0.27}(stat) +- 0.09(syst))*10^-6 and BR(B+- --> chi_c0 K+-) * BR(chi_c0 --> K+ K-) = (1.49^{+0.36}_{-0.34}(stat) +- 0.11(syst))* 10^-6. Using the known values for the chi_c0 decays branching fractions, we combine these results to obtain BR(B+- --> chi_c0 K+-) = (2.7+-0.7)* 10^-4.

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arXiv2003

Search for the B Meson Decay to eta' phi

We present preliminary results of a search for the decay B0 -> eta' phi. The data were recorded with the BaBar detector at the PEP-II asymmetric-energy B-meson Factory at SLAC and correspond to 89 million B B-bar pairs produced in e+e- annihilation at the Upsilon(4S) resonance. We find no evidence for a signal and set a 90% CL upper limit of BF(B0 -> eta' phi) < 1.0 x 10^-6

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arXiv2003

Measurement of the Branching Fraction and Polarization for the Decay B- to D*0 K*-

We present a study of the decay B- -> D*0 K*- based on a sample of 86 million Upsilon(4S) -> BBbar decays collected between 1999 and 2002 with the BaBar detector at the PEP-II asymmetric-energy B-Factory at SLAC. We measure the branching fraction B(B- -> D*0 K*-) = 8.3 +/- 1.1 (stat)} +/- 1.0 (syst) x 10e-4, and the fraction of longitudinal polarization in this decay to be GammaL/Gamma = 0.86 +/- 0.06 +/- (stat) +/- 0.03 (syst).

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arXiv2003

Measurements of CP-violating Asymmetries and Branching Fractions in B Meson Decays to eta' K

We present measurements of the branching fractions of the decays B+ -> eta' K+ and B0 -> eta' K0. For B0 -> eta' K0s we also measure the time dependent CP-violation parameters S and C, and for B+ ->eta' K+ the time-integrated charge asymmetry Ach. The data sample corresponds to 88.9 million BBbar pairs produced by e+e- annihilation at the Upsillon(4S). The results are B(B+->eta'K+) = (76.9 +/- 3.5 +/- 4.4)*10^-6, B(B0->eta'K0) = (60.6 +/- 5.6 +/- 4.6)*10^-6, S = 0.02+/-0.34 +/- 0.03, C = 0.10+/-0.22 +/- 0.04, and Ach = 0.037 +/- 0.045+/- 0.011.

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arXiv2003

Evidence for the Rare Decay B -> K*ll and Measurement of the B -> Kll Branching Fraction

We present evidence for the flavor-changing neutral current decay $B\to K^*\ell^+\ell^-$ and a measurement of the branching fraction for the related process $B\to K\ell^+\ell^-$, where $\ell^+\ell^-$ is either an $e^+e^-$ or $μ^+μ^-$ pair. These decays are highly suppressed in the Standard Model, and they are sensitive to contributions from new particles in the intermediate state. The data sample comprises $123\times 10^6$ $Υ(4S)\to B\bar{B}$ decays collected with the Babar detector at the PEP-II $e^+e^-$ storage ring. Averaging over $K^{(*)}$ isospin and lepton flavor, we obtain the branching fractions ${\mathcal B}(B\to K\ell^+\ell^-)=(0.65^{+0.14}_{-0.13}\pm 0.04)\times 10^{-6}$ and ${\mathcal B}(B\to K^*\ell^+\ell^-)=(0.88^{+0.33}_{-0.29}\pm 0.10)\times 10^{-6}$, where the uncertainties are statistical and systematic, respectively. The significance of the $B\to K\ell^+\ell^-$ signal is over $8σ$, while for $B\to K^*\ell^+\ell^-$ it is $3.3σ$.

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arXiv2003

Study of the Decays B- -> D(*)+ pi- pi-

We report on analyses of $B^-$ mesons decaying into $D^{*+}π^-π^-$ and $D^+π^-π^-$ final states using 89 million $B^-$ decays collected by the BABAR detector at the PEP-II asymmetric-energy $B$ Factory. Preliminary measurements are given for the inclusive branching fractions for $B^- \to D^{*+}π^-π^-$ and $B^- \to D^+π^-π^-$, and for the exclusive branching fractions for $B^- \to D_1(2420)^0π^-$ and $B^- \to D_2^{*}(2460)^0π^-$, where $D_1(2420)^0$ and $D_2^{*}(2460)^0$ are the two narrow $c\bar u$ $P$-wave states. The ratio ${\mathcal{B}}(B^- \to D_2^*(2460)^0π^-)/{\mathcal{B}}(B^- \to D_1(2420)^0π^-)$ is measured to be $0.80 \pm 0.07 \pm 0.16$.

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arXiv2003

Measurement of |Vcb| using B0 -> D* l nu_l Decays

A preliminary measurement of |Vcb| and the branching fraction BR(B0 -> D* l nu_l) has been performed based on a sample of about 55,700 B0 -> D* l nu_l decays recorded with the BaBar detector. The decays are identified in the D* -> D0 pi final state, with the D0 reconstructed in three different decay modes. The differential decay rate is measured as a function of the relativistic boost of the D* in the B0 rest frame. The value of the differential decay rate at `zero recoil', namely the point at which the D* is at rest in the B0 frame, is predicted in Heavy Quark Effective Theory as a kinematic factor times F(1)|Vcb|, where F(1) is the unique form factor governing the decay. We extrapolate the measured differential decay rate to the zero recoil point and obtain F(1)|Vcb|=(34.03+-0.24+-1.31) x 10^-3. Using a theoretical calculation for F(1) we extract |Vcb| = (37.27+-0.26(stat.)+-1.43(syst.)+1.5-1.2(theo.) x 10^-3. From the integrated decay rate we obtain BR(B0 -> D* l nu_l) = (4.68+-0.03+-0.29)%.

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