arXiv subjects

B. Aubert et al

Publications and source records attributed to B. Aubert et al.

9 recordsLinked to original sources

arXiv2008

Measurements of Partial Branching Fractions for Bbar --> X_u ell nubar and Determination of |V_{ub}|

We present partial branching fractions for inclusive charmless semileptonic B decays Bbar --> X_u ell nubar, and the determination of the CKM matrix element |V_{ub}|. The analysis is based on a sample of 383 million Y(4S) decays into B Bbar pairs collected with the BaBar detector at the PEP-II e+ e- storage rings. We select events using either the invariant mass M_X of the hadronic system, the invariant mass squared, q^2, of the lepton and neutrino pair, the kinematic variable P_+ or one of their combinations. We then determine partial branching fractions in limited regions of phase space: Delta B = (1.18 +- 0.09_{stat.} +- 0.07_{syst.} +- 0.01_{theo.}) x 10^{-3} (M_X < 1.55 GeV/c^2), Delta B = (0.95 +- 0.10_{stat.} +- 0.08_{syst.} +- 0.01_{theo.}) x 10^{-3} (P_+ < 0.66 GeV/c), and Delta B = (0.81 +- 0.08_{stat.} +- 0.07_{syst.} +- 0.02_{theo.}) x 10^{-3} (M_X < 1.7 GeV/c^2, q^2 > 8 GeV^2/c^4). Corresponding values of |V_{ub}| are extracted using several theoretical calculations.

hep-ex↗

arXiv2007

Search for the decay B+ -> K+ tau-/+ mu+/-

We present a search for the lepton flavor violating decay B+ --> K+ tau-/+ mu+/- using 383 million B Bbar events collected by the BABAR experiment. The branching fraction for this decay can be substantially enhanced in new physics models. The kinematics of the tau from the signal B decay are inferred from the K+, mu, and other B in the event, which is fully reconstructed in one of a variety of hadronic decay modes, allowing the signal B candidate to be fully reconstructed. We observe no excess of events over the expected background and set a limit of B(B+ --> K+ tau mu) < 7.7 x 10^-5 at 90% confidence level, where the branching fraction is for the sum of the K+ tau- mu+ and K+ tau+ mu- final states. We use this result to improve a model-independent bound on the energy scale of flavor-changing new physics.

hep-ex↗

arXiv2007

Measurement of CP Asymmetries in B0 --> K0S K0S K0S Decays

We present measurements of the time-dependent CP-violating asymmetries in B0 --> K0S K0S K0S decays based on 384 million Y(4S) decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We obtain the CP asymmetry parameters C = 0.02 +/- 0.21 +/- 0.05 and S = -0.71 +/- 0.24 +/- 0.04, where the first uncertainties are statistical and the second systematic. These results are consistent with standard model expectations.

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arXiv2007

Branching fraction and CP-violation charge asymmetry measurements for B-meson decays to eta K+-, etapi+-, eta'K, eta'pi+-, omega K, and omegapi+-

We present measurements of the branching fractions for B0 meson decays to eta'K0 and omegaK0, and of the branching fractions and CP-violation charge asymmetries for B+ meson decays to etapi+, etaK+, eta'pi+, eta'K+, omegapi+, and omegaK+. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 383 million BBbar pairs produced in e+e- annihilation. The measurements agree with previous results; we find no evidence for direct CP violation.

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arXiv2006

Measurement of the Branching Fractions for the Decays B+ -> rho+ gamma, B0 -> rho0 gamma, and B0 -> omega gamma

We present preliminary results of a search for the decays B+ -> rho+ gamma, B0 -> rho0 gamma, and B0 -> omega gamma. The analysis is based on data containing 347 million BB events recorded with the BaBar detector at the PEP-II B factory. We measure branching fractions of BF(B+ -> rho+ gamma) = (1.06^{+0.35}_{-0.31} +- 0.09) x 10^{-6} and BF(B+ -> rho0 gamma) = (0.77^{+0.21}_{-0.19} +- 0.07) x 10^{-6}, where the first errors are statistical and the second systematic, and set a 90% C.L. upper limit of BF(B0 -> omega gamma) < 0.84 10^{-6}. Assuming isospin relations between the three branching fractions, these results are used to determine the CKM matrix element ratio |V_td/V_ts| = 0.171^{+0.018}_{-0.021}(exp.)^{+0.017}_{-0.014}(theor.).

hep-ex↗

arXiv2006

Search for the decay B0 to a1 rho

We present a search for the rare B-meson decay B0 to a1+- rho-+ with a_1+- to pi+ pi- pi+-. We use (110 +/- 1.2) x 10^6 Upsilon(4S) to BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. We obtain an upper limit of 30 x 10-6 (90% C.L.) for the branching fraction product B(B0 to a_1+- rho-+)B(a_1+- to pi+ pi- pi+-), where we assume that the a_1+- decays exclusively to rho0 pi+-.

hep-ex↗

arXiv2005

Search for the Rare Decays B0 -> Ds(*)+ a0(2)-

We have searched for the decays $B^0 \rightarrow D_s^{+}a_0^-$, $B^0 \rightarrow D_s^{*+}a_0^-$, $B^0 \rightarrow D_s^{+}a_2^-$ and $B^0 \rightarrow D_s^{*+}a_2^-$ in a sample of about 230 million $Υ(4S) \rightarrow B{\bar B}$ decays collected with the {\sl BaBar} detector at the PEP-II asymmetric-energy $B$-factory at SLAC. We find no evidence for these decays and set upper limits at 90\% C.L. on the branching fractions: ${\cal B}(B^0 \rightarrow D_s^+ a_0^-) < 1.9\times 10^{-5}$, ${\cal B}(B^0 \rightarrow D_s^{*+} a_0^-) < 3.6\times 10^{-5}$, ${\cal B}(B^0 \rightarrow D_s^+ a_2^-) < 1.9 \times 10^{-4}$, and ${\cal B}(B^0 \rightarrow D_s^{*+} a_2^-) < 2.0\times 10^{-4} $.

hep-ex↗

arXiv2004

Limit on the B0->rho0rho0 Branching Fraction and Implications for the CKM Angle alpha

We search for the decay B0 -> rho0 rho0 in a data sample of about 227 million Upsilon(4S)-> BBbar decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find no significant signal and set an upper limit of 1.1*10^-6 at 90% CL on the branching fraction. As a result, the uncertainty due to penguin contributions on the CKM unitarity angle alpha measured in B -> rho rho decays is 11 degrees at 68% CL.

hep-ex↗

arXiv2002

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

We present results from a search for the flavor-changing neutral current decays $B\to K\ell^+\ell^-$ and $B\to K^*\ell^+\ell^-$, where $\ell^+\ell^-$ is either an $e^+e^-$ or $μ^+μ^-$ pair. The data sample comprises $22.7\times 10^6$ $Υ(4S)\to B\bar B$ decays collected with the BABAR detector at the PEP-II $B$ Factory. We obtain the 90% C.L. upper limits ${\mathcal B}(B\to K\ell^+\ell^-)< 0.50\times 10^{-6}$ and ${\mathcal B}(B\to K^*\ell^+\ell^-)<2.9\times 10^{-6}$, close to Standard Model predictions for these branching fractions. We have also obtained limits on the lepton-family-violating decays $B\to Ke^{\pm}μ^{\mp}$ and $B\to K^{*}e^{\pm}μ^{\mp}$.

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