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We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega. The measur ement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06 (syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.
We present an update on total and partial branching fractions and on CP asymmetries in the semi-inclusive decay B -> Xs l+l-. Further, we summarize our results on branching fractions and CP asymmetries for semi-inclusive and fully-inclusive B -> Xs g amma decays. We present the first result on the CP asymmetry difference of charged and neutral B -> Xs gamma$ decays yielding the first constraint on the ratio of Wilson coefficients Im (C8/C7).
78 - J.P. Lees 2014
Based on a sample of 500 million $e^+e^- to cbar c$ events recorded by the BaBar detector at c.m. energies of close to 10.6 GeV, we report on a study of the decay $D^0 to pi^- e^+ u_e$. We measure the ratio of branching fractions $R_D = {cal B}(D^0 to pi^- e^+ u_e)/{cal B}(D^0 to K^- pi^+) = 0.0713 pm 0.0017_{stat.} pm 0.0024_{syst.}$, and use the present world average for ${cal B}(D^0 to K^- pi^+)$ to obtain ${cal B}(D^0 to pi^- e^+ u_e) = (2.770 pm 0.068_{{rm stat.}} pm 0.092_{{rm syst.}} pm 0.037_{{rm ext.}})times 10^{-3}$ where the third error accounts for the uncertainty on the branching fraction for the reference channel. The measured dependence of the differential branching fraction on $q^2$, the four-momentum transfer squared between the $D$ and the $pi$ meson, is compared to various theoretical predictions for the hadronic form factor, $f_{+,D}^{pi}(q^2)$, and the normalization $|V_{cd}| times f_{+,D}^{pi}(q^2=0)=0.1374pm0.0038_{{rm stat.}} pm0.0022_{{rm syst.}} pm0.0009_{{rm ext.}}$ is extracted from a fit to data. Using the most recent LQCD prediction of $f_{+,D}^{pi}(q^2=0)=0.666 pm 0.029$, we obtain $|V_{cd}|=0.206 pm 0.007_{rm exp.} pm 0.009_{rm LQCD}$. Assuming instead, $|V_{cd}|=|V_{us}|=0.2252 pm 0.0009$, we obtain $f_{+,D}^{pi}(q^2=0)=0.610 pm 0.020_{rm exp.} pm 0.005_{rm ext.}$. The $q^2$ dependence of $f_{+,D}^{pi}(q^2)$ is compared to a variety of multi-pole parameterizations. This information is applied to $B^0 to pi^- e^+ u_e$ decays and, combined with an earlier $B^0 to pi^- e^+ u_e$ measurement by BaBar, is used to derive estimates of $|V_{ub}|$.
245 - John Walsh 2014
I report here recent measurements of observables from the inclusive decays $Bto X_sgamma$ and $Bto X_sell^+ell^-$. Included are measurements of the branching fractions and CP asymmetries for both channels, as well as the forward-backward lepton asymm etry in inclusive $Bto X_sell^+ell^-$ decays, which is the first measurement of this quantity.
We measure the direct CP violation asymmetry, A_CP, in B to X_s gamma and the isospin difference of the asymmetry, Delta A_CP, using 429 fb^-1 of data collected at Upsilon(4S) resonance with the BaBar detector at the PEP-II asymmetric-energy e+e- sto rage rings operating at the SLAC National Accelerator Laboratory. B mesons are reconstructed from 10 charged B final states and 6 neutral B final states. We find A_CP = +(1.7 +- 1.9 +- 1.0)%, which is in agreement with the Standard Model prediction and provides an improvement on the world average. Moreover, we report the first measurement of the difference between A_CP for charged and neutral decay modes, Delta A_CP = +(5.0 +- 3.9 +- 1.5)%. Using the value of Delta A_CP, we also provide 68% and 90% confidence intervals on the imaginary part of the ratio of the Wilson coefficients corresponding to the chromo-magnetic dipole and the electromagnetic dipole transitions.
We study the processes $e^+ e^-to K_S^0 K_L^0 gamma$, $K_S^0 K_L^0 pi^+pi^-gamma$, $K_S^0 K_S^0 pi^+pi^-gamma$, and $K_S^0 K_S^0 K^+K^-gamma$, where the photon is radiated from the initial state, providing cross section measurements for the hadronic states over a continuum of center-of-mass energies. The results are based on 469 fb$^{-1}$ of data collected with the BaBar detector at SLAC. We observe the $phi(1020)$ resonance in the $K_S^0 K_L^0$ final state and measure the product of its electronic width and branching fraction with about 3% uncertainty. We present a measurement of the $e^+ e^-to K_S^0 K_L^0 $ cross section in the energy range from 1.06 to 2.2 GeV and observe the production of a resonance at 1.67 GeV. We present the first measurements of the $e^+ e^-to K_S^0 K_L^0 pi^+pi^-$, $K_S^0 K_S^0 pi^+pi^-$, and $K_S^0 K_S^0 K^+K^-$ cross sections, and study the intermediate resonance structures. We obtain the first observations of jpsi decay to the $K_S^0 K_L^0 pi^+pi^-$, $K_S^0 K_S^0 pi^+pi^-$, and $K_S^0 K_S^0 K^+K^-$ final states.
We describe searches for B meson decays to the charmless vector-vector final states omega omega and omega phi with 471 x 10^6 B Bbar pairs produced in e+ e- annihilation at sqrt(s) = 10.58 GeV using the BABAR detector at the PEP-II collider at the SL AC National Accelerator Laboratory. We measure the branching fraction B(B0 --> omega omega) = (1.2 +- 0.3 +0.3-0.2) x 10^-6, where the first uncertainty is statistical and the second is systematic, corresponding to a significance of 4.4 standard deviations. We also determine the upper limit B(B0 --> omega phi) < 0.7 x 10^-6 at 90% confidence level. These measurements provide the first evidence for the decay B0 --> omega omega, and an improvement of the upper limit for the decay B0 --> omega phi.
We study the decay $bar{B}^{0}rightarrowLambda_{c}^{+}bar{p}pi^{+}pi^{-}$, reconstructing the Lambda_{c}^{+} baryon in the $p K^{-}pi^{+}$ mode, using a data sample of $467times 10^{6}$ $Bbar{B}$ pairs collected with the BaBar detector at the PEP-2 s torage rings at SLAC. We measure branching fractions for decays with intermediate $Sigma_{c}$ baryons to be ${cal B}[bar{B}^{0}rightarrowSigma_{c}(2455)^{++}bar{p}pi^{-}]=(21.3 pm 1.0 pm 1.0 pm 5.5) times 10^{-5}$, ${cal B}[bar{B}^{0}rightarrowSigma_{c}(2520)^{++}bar{p}pi^{-}]=(11.5pm 1.0 pm 0.5 pm 3.0)times 10^{-5}$, ${cal B}[bar{B}^{0}rightarrowSigma_{c}(2455)^{0}bar{p}pi^{+}]=(9.1 pm 0.7 pm 0.4 pm 2.4)times10^{-5}$, and ${cal B}[bar{B}^{0}rightarrowSigma_{c}(2520)^{0}bar{p}pi^{+}]= (2.2 pm 0.7 pm 0.1pm 0.6) times 10^{-5}$, where the uncertainties are statistical, systematic, and due to the uncertainty on the $Lambda_{c}^{+}rightarrowprotonKmpi^{+}$ branching fraction, respectively. For decays without $Sigma_{c}(2455)$ or $Sigma_{c}(2520)$ resonances, we measure ${cal B}[bar{B}^{0}rightarrowLambda_{c}^{+}bar{p}pi^{+}pi^{-}]_{mathrm{non-Sigma_{c}}}=(79 pm 4 pm 4 pm 20)times10^{-5}$. The total branching fraction is determined to be ${cal B}[bar{B}^{0}rightarrowLambda_{c}^{+}bar{p}pi^{+}pi^{-}]_{mathrm{total}}=(123 pm 5 pm 7 pm 32)times10^{-5}$. We examine multibody mass combinations in the resonant three-particle $Sigma_{c}bar{p}pi$ final states and in the four-particle $Lambda_{c}^{+}bar{p}pi^{+}pi^{-}$ final state, and observe different characteristics for the $bar{p}pi$ combination in neutral versus doubly-charged $Sigma_{c}$ decays.
125 - Valentina Santoro 2012
We present recent results on charmonium and charmonium-like states from the BaBar B-factory located at the PEP-II asymmetric energy $e^{+}e^{-}$ storage ring at the SLAC National Accelerator Laboratory.
We study the process $e^+e^-topsi(2S)pi^{+}pi^{-}$ with initial-state-radiation events produced at the PEP-II asymmetric-energy collider. The data were recorded with the BaBar detector at center-of-mass energies at and near the $Upsilon(mathrm{nS})$ (n = 2, 3, 4) resonances and correspond to an integrated luminosity of 520$fb^{-}$. We investigate the $psi(2S)pi^{+}pi^{-}$ mass distribution from 3.95 to 5.95 $GeV/c^{2}$, and measure the center-of-mass energy dependence of the associated $e^+e^-to psi(2S)pi^{+}pi^{-}$ cross section. The mass distribution exhibits evidence of two resonant structures. A fit to the $psi(2S)pi^{+}pi^{-}$ mass distribution corresponding to the decay mode $psi(2S)to J/psi pi^{+}pi^{-}$ yields a mass value of $4340 pm16$ (stat) $pm 9$ (syst) ${mathrm {MeV/c^{2}}}and a width of $94 pm 32$ (stat) $pm 13$ (syst) MeV for the first resonance, and for the second a mass value of $4669 pm 21$ (stat) $pm 3$ (syst) ${mathrm {MeV/c^{2}}}$ and a width of $104 pm 48$ (stat) $pm 10$ (syst) MeV. In addition, we show the $pi^{+}pi^{-}$ mass distributions for these resonant regions.
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