Showing papers by "B. Stugu published in 2002"

Measurement of the CP asymmetry amplitude sin2β with B0 mesons

Abstract: We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 88 x 10(6) Upsilon(4S)-->B(-)B decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B(0) or B(-0) from its decay products. The amplitude of the CP asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay-time distributions in such events. We measure sin2beta=0.741+/-0.067(stat)+/-0.034(syst) and |lambda|=0.948+/-0.051(stat)+/-0.030(syst). The magnitude of lambda is consistent with unity, in agreement with the standard model expectation of no direct CP violation in these modes.

Measurement of theCPAsymmetry Amplitudesin2βwithB0Mesons

Abstract: We present results on time-dependent $CP$ asymmetries in neutral $B$ decays to several $CP$ eigenstates. The measurements use a data sample of about $88\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}B\overline{B}$ decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at SLAC. We study events in which one neutral $B$ meson is fully reconstructed in a final state containing a charmonium meson and the other $B$ meson is determined to be either a ${B}^{0}$ or ${\overline{B}}^{0}$ from its decay products. The amplitude of the $CP$ asymmetry, which in the standard model is proportional to $\mathrm{sin} 2\ensuremath{\beta}$, is derived from the decay-time distributions in such events. We measure $\mathrm{sin} 2\ensuremath{\beta}=0.741\ifmmode\pm\else\textpm\fi{}0.067\mathrm{(}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{)}\ifmmode\pm\else\textpm\fi{}0.034\mathrm{(}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{)}$ and $|\ensuremath{\lambda}|=0.948\ifmmode\pm\else\textpm\fi{}0.051\mathrm{(}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{)}\ifmmode\pm\else\textpm\fi{}0.030\mathrm{(}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{)}$. The magnitude of $\ensuremath{\lambda}$ is consistent with unity, in agreement with the standard model expectation of no direct $CP$ violation in these modes.

Measurements of branching fractions and CP-violating asymmetries in B0-->pi+pi-, K+pi-, K+K- decays.

Abstract: We present measurements of branching fractions and CP-violating asymmetries for two-body neutral B meson decays to charged pions and kaons based on a sample of about 88x10(6) Upsilon(4S)-->BB decays. From a time-independent fit we measure the charge-averaged branching fractions B(B0-->pi+pi-)=(4.7+/-0.6+/-0.2)x10(-6), B(B0-->K+pi-)=(17.9+/-0.9+/-0.7)x10(-6), and the direct CP-violating charge asymmetry A(Kpi)=-0.102+/-0.050+/-0.016 [-0.188,-0.016], where the ranges in square brackets indicate the 90% confidence intervals. From a time-dependent fit we measure the B0-->pi+pi- CP-violating parameters S(pipi)=0.02+/-0.34+/-0.05 [-0.54,+0.58] and C(pipi)=-0.30+/-0.25+/-0.04 [-0.72,+0.12].

Measurements of branching fractions and CP-violating asymmetries in B0 → π+π-, K+π-, K+K- decays

Abstract: We present measurements of branching fractions and CP-violating asymmetries for two-body neutral B meson decays to charged pions and kaons based on a sample of about 88*106 U(4S) BB decays. From a time-independent fit we measure the charge-averaged branching fractions B(B0 p+p-)=(4.7+-0.6+-0.2)*10-6, B(B0 K+p-)=(17.9+-0.9+-0.7)*10-6, and the direct CP-violating charge asymmetry AKp=-0.102+-0.050+-0.016 [-0.188,-0.016], where the ranges in square brackets indicate the 90% confidence intervals. From a time-dependent fit we measure the B0 -> p+p- CP-violating parameters Spp=0.02+-0.34+-0.05 [-0.54,+0.58] and Cpp=-0.30+-0.25+-0.04 [-0.72,+0.12]. [on SciFinder (R)]

Study of time-dependent CP-violating asymmetries and flavor oscillations in neutral B decays at the Υ(4S)

Abstract: We present a measurement of time-dependent CP-violating asymmetries in neutral B meson decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The data sample consists of 29.7 ${\rm fb}^{-1}$ recorded at the $\Upsilon(4S)$ resonance and 3.9 ${\rm fb}^{-1}$ off-resonance. One of the neutral B mesons, which are produced in pairs at the $\Upsilon(4S)$, is fully reconstructed in the CP decay modes $J/\psi K^0_S$, $\psi(2S) K^0_S$, $\chi_{c1} K^0_S$, $J/\psi K^{*0}$ ($K^{*0}\to K^0_S\pi^0$) and $J/\psi K^0_L$, or in flavor-eigenstate modes involving $D^{(*)}\pi/\rho/a_1$ and $J/\psi K^{*0}$ ($K^{*0}\to K^+\pi^-$). The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. The proper time elapsed between the decays is determined by measuring the distance between the decay vertices. A maximum-likelihood fit to this flavor eigenstate sample finds $\Delta m_d = 0.516\pm 0.016 {\rm (stat)} \pm 0.010 {\rm (syst)} {\rm ps}^{-1}$. The value of the asymmetry amplitude $\sin2\beta$ is determined from a simultaneous maximum-likelihood fit to the time-difference distribution of the flavor-eigenstate sample and about 642 tagged $B^0$ decays in the CP-eigenstate modes. We find $\sin2\beta=0.59\pm 0.14 {\rm (stat)} \pm 0.05 {\rm (syst)}$, demonstrating that CP violation exists in the neutral B meson system. (abridged)

Silicon microstrip detectors for the ATLAS SCT

Abstract: The ATLAS Semiconductor Tracker at the Large Hadron Collider (LHC) will incorporate ∼20,000 individual silicon microstrip sensors representing ∼60 m 2 of silicon. Production and delivery of the sensors is already underway and scheduled for completion by late 2002. The sensors have been optimised for operation in the harsh radiation environment of the LHC, and subjected to an extensive qualification program in which their pre- and post-irradiation characteristics have been evaluated. The sensor design features are reviewed, together with their electrical characteristics and the Quality Control procedures adopted by ATLAS during production.

Search for the rare decays B-->Kl(+)l(-) and B-->K(*)l(+)l(-).

Abstract: We present results from a search for the flavor-changing neutral current decays B-->Kl(+)l(-) and B-->K(*)l(+)l(-), where l(+)l(-) is either an e(+)e(-) or mu(+)mu(-) pair. The data sample comprises 22.7 x 10(6) Upsilon(4S)-->B(-)B decays collected with the BABAR detector at the PEP-II B Factory. We obtain the 90% C.L. upper limits B(B-->Kl(+)l(-)) K(*)l(+)l(-)) Ke+/-mu(-/+) and B-->K(*)e(+/-)mu(-/+).

Determination of the branching fraction for inclusive decays $B \to X_{s} \gamma$

Abstract: We present a preliminary determination of the inclusive branching fraction for the rare radiative penguin transition B -> X_{s} gamma. The measurement is based on a data sample of 60 million BB pairs collected between 1999 and 2001 with the BaBar detector at the PEPII asymmetric-energy e+e- B Factory at SLAC. We study events containing a high-energy photon from one B (or Bbar) decay and a tagging primary lepton from the decay of the other B meson. By this means, we are able to reduce a significant component of the background without introduction of model dependent uncertainties in the event selection efficiency. We determine the branching fraction BR(B->X_{s} gamma)=3.88 +-0.36(stat.)+-0.37(sys.) +0.43-0.23(model.)x10^{-4}, which is consistent with Standard Model predictions and provides a constraint on possible new physics contributions to the electromagnetic penguin amplitude in B decays.

Search for T and CP Violation in B0--B0 Mixing with Inclusive Dilepton Events.

Abstract: We report the results of a search for T, CP, and CPT violation in B^0-B^0 mixing using an inclusive dilepton sample collected by the BABAR experiment at the PEP-II B factory. Using a sample of 232×10^6 BB pairs, we measure the T and CP violation parameter |q/p|-1=(-0.8±2.7(stat)±1.9(syst))×10^(-3), and the CPT and CP parameters Imz=(-13.9±7.3(stat)±3.2(syst))×10^(-3) and ΔΓ×Rez=(-7.1±3.9(stat)±2.0(syst))×10^(-3) ps^(-1). The statistical correlation between the measurements of Imz and ΔΓ×Rez is 76%.

Measurement of B-0-(B)over-bar(0) flavor oscillations in hadronic B-0 decays

Abstract: Flavor oscillations of neutral B mesons have been studied in e+e- annihilation data collected with the BABAR detector at center-of-mass energies near the upsilon(4S) resonance. The data sample used for this purpose consists of events in which one B0 meson is reconstructed in a hadronic decay mode, while the flavor of the recoiling B0 is determined with a tagging algorithm that exploits the correlation between the flavor of the heavy quark and the charges of its decay products. From the time development of the observed mixed and unmixed final states, we determine the B0-B-0 oscillation frequency deltamd to be 0.516+/-0.016(stat)+/-0.010(syst) ps-1.

Measurement of Ds+ and Ds*+ production in B meson decays and from continuum e+e- annihilation at √s = 10.6 GeV

Abstract: New measurements of Ds+ and Ds*+ meson production rates from B decays and from qqbar continuum events near the Y(4S) resonance are presented. Using 20.8 fb-1 of data on the Y(4S) resonance and 2.6 fb-1 off resonance, we find the inclusive branching fractions BR(B --> Ds+ X) = (10.93+/-0.19+/-0.58+/-2.73)% and BR(B --> Ds*+ X) = (7.9+/-0.8+/-0.7+/-2.0)%, where the first error is statistical, the second is systematic, and the third is due to the Ds+ --> phi pi+ branching fraction uncertainty. The branching fractions SumBR(B --> Ds(*)+ Dbar(*)) = (5.07+/-0.14+/-0.30+/-1.27)% and SumBR(B --> Ds*+ Dbar(*)) = (4.1+/-0.2+/-0.4+/-1.0)% are determined from the Ds(*)+ momentum spectra.

Measurement of the B0-B̄0 oscillation frequency with inclusive dilepton events

Abstract: The B0-B-0 oscillation frequency has been measured with a sample of 23 x 10(6) BB- pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives deltamd = 0.493+/-0.012(stat)+/-0.009(syst) ps-1.

Search for the rare decays $B \to Kl^+l^-$ and $B \to K^*l^+l^-$

Abstract: 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 $\mu^+\mu^-$ pair. The data sample comprises $22.7\times 10^6$ $\Upsilon(4S)\to B\bar B$ 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 $B\to Ke^{\pm}\mu^{\mp}$ and $B\to K^{*}e^{\pm}\mu^{\mp}$.

Study of CP-violating asymmetries in B-0 ->pi(+) pi(-), K+ pi(-) decays

Abstract: We present a measurement of the time-dependent CP-violating asymmetries in neutral B decays to the {pi}{sup +}{pi}{sup -} CP eigenstate, and an updated measurement of the charge asymmetry in B{sup 0} {yields} K{sup +} {pi}{sup -} decays. In a sample of 33 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the SLAC PEP-II asymmetric B Factory, we find 65{sub -11}{sup +12} {pi}{sup +} {pi}{sup -} and 217 {+-} 18 K{sup +}{pi}{sup -} candidates and measure the asymmetry parameters S{sub {pi}{pi}} = 0.03{sub -0.56}{sup +0.53} {+-} 0.11, C{sub {pi}{pi}} = -0.25{sub -0.47}{sup +0.45} {+-} 0.14, and {Alpha}{sub K{pi}} = -0.07 {+-} 0.08 {+-} 0.02, where the first error is statistical and the second is systematic.

Study of B±→J/ψπ± and B±→J/ψK± decays: Measurement of the ratio of branching fractions and search for direct CP-violating charge asymmetries

Abstract: We have studied the B{sup {+-}} {yields} J/{psi}{pi}{sup {+-}} and B{sup {+-}} {yields} J/{psi} K{sup {+-}} decays using a 20.7 fb{sup -1} data set collected with the BABAR detector. We observe a signal of 51 {+-} 10 B{sup {+-}} {yields} J/{psi}{pi}{sup {+-}} events and determine the ratio {Beta}(B{sup {+-}} {yields} J/{psi}{pi}{sup {+-}})/{Beta}(B{sup {+-}} {yields} J/{psi} K{sup {+-}}) to be [3.91 {+-} 0.78(stat.) {+-} 0.19(syst.)]%. The CP-violating charge asymmetries for the B{sup {+-}} {yields} J/{psi} {pi}{sup {+-}} and B{sup {+-}} {yields} J/{psi} K{sup {+-}} decays are determined to be {Alpha}{sub {pi}} = 0.01 {+-} 0.22(stat.) {+-} 0.01(syst.) and {Alpha}{sub K} = 0.003 {+-} 0.030(stat.) {+-} 0.004(syst.).

Direct CP violation searches in charmless hadronic B meson decays

Abstract: We search for direct CP violation in charmless hadronic B decays observed in a sample of about 22.7 million B (B) over bar pairs collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)e(-) collider. We measure the following charge asymmetries: A(CP)(B+/- --> eta'K+/-) = -0.11 +/- 0.11 +/- 0.02, A(CP)(B+/- --> omegapi+/-) = -0.01 +/- (0.29)(0.31) +/- 0.03, A(CP)(B+/- -->phiK+/-)= -00.5 +/-0.20+/-0.03, A(CP)(B+/- --> phiK*=/-)= -0.43 (+0.36)(-0.30) +/-0.06, and A(CP)((B) over bar (0) --> phi(K) over bar*(0)) = 0.00 +/- 0.27 +/- 0.03.

Measurement of the B-0 lifetime with partially reconstructed B-0 -> D(-)l(+)nu(l) decays

Abstract: The B(0) lifetime was measured with a sample of 23 million BB pairs collected by the BABAR detector at the PEP-II e(+)e(-) storage ring during 1999 and 2000. Events from the semileptonic decay B(0)-->D(*-)l(+)nu(l) have been selected with a partial reconstruction method in which only the charged lepton and the slow pi from the D*--->D(0)pi(-) decay are reconstructed. The result is tau(B(0)) = 1.529+/-0.012(stat)+/-0.029(syst) ps.

Improved Measurement of the CP-Violating Asymmetry Amplitude sin2beta

Abstract: We present updated results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 62 million {Upsilon}(4S) {yields} B{bar B} decays collected between 1999 and 2001 by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. In this sample we study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2{beta}, is derived from the decay time distributions in such events. We measure sin2{beta} = 0.75 {+-} 0.09 (stat) {+-} 0.04 (syst) and |lambda| = 0.92 {+-} 0.06 (stat) {+-} 0.02 (syst). The latter is consistent with the Standard Model expectation of no direct CP violation. These results are preliminary.

Search for the exclusive radiative decays b ---> rho gamma and b0 ---> omega gamma

Abstract: A search for the exclusive radiative decays B {yields} {rho}(770){gamma} and B{sup 0} {yields} {omega}(782){gamma} is performed on a sample of 84 million B{bar B} events collected by the BaBar detector at the PEP-II asymmetric e{sup +}e{sup -} collider. No significant signal is seen in any of the channels. They set preliminary upper limits of {Beta}[B{sup 0} {yields} {rho}{sup 0}{gamma}] < 1.4 x 10{sup -6}, {Beta}[B{sup +} {yields} {rho}{sup +}{gamma}] < 2.3 x 10{sup -6} and {Beta}[B{sup 0} {yields} {omega}{gamma}] < 1.2 x 10{sup -6} at 90% Confidence Level. Combining these into a single limit on the generic process B {yields} {rho}{gamma}, they find the preliminary limit {Beta}[B {yields} {rho}{gamma}] < 1.9 x 10{sup -6} corresponding, to a limit of {Beta}[B {yields} {rho}{gamma}]/{Beta}[B {yields} K*{gamma}] < 0.047 at 90% Confidence Level.

Radiation studies of silicon-microstrip detectors for use in ATLAS and SCT

Abstract: Silicon detectors designed for use in ATLAS at CERN's Large Hadron Collider, Geneva, Switzerland, are shown to operate satisfactorily after irradiation with 3/spl times/10/sup 14/ (24 GeV/c protons)/cm/sup 2/. No breakdown effects are seen with the detectors biased up to 500 V.

Measurement of the first hadronic spectral moment from semileptonic B decays

Abstract: A preliminary determination of the first moment of the hadronic mass distribution 〈M2 X −mD〉 in semileptonic B decays has been obtained as a function of the minimum lepton momentum, ranging from 0.9 to 1.6 GeV/c. The measurement is based on a new technique involving BB events in which one fully reconstructed B meson decays hadronically and the recoiling B decays semileptonically. The mass of the hadrons in the semileptonic decay is determined from a kinematic fit to the whole event. For different minimum lepton momenta, the mass distribution is decomposed into contributions from various charm resonant states and a non-resonant contribution, allowing for the determination of the first moment. From these moments the Heavy Quark Effective Theory (HQET) parameters λ1 and Λ can be derived. For lepton momenta in the B rest frame above 1.5GeV/c, we find a first moment that is compatible with existing measurements. However, if we extend the measurement to lower values of lepton momenta, the data can only be described by Operator Product Expansion calculations if we use significantly different values for Λ and λ1 than obtained from earlier measurements based on lepton momentum spectra and the photon spectrum in b → sγ transitions. Contributed to the 31st International Conference on High Energy Physics, 7/24—7/31/2002, Amsterdam, The Netherlands Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309 Work supported in part by Department of Energy contract DE-AC03-76SF00515. The BABAR Collaboration, B. Aubert, D. Boutigny, J.-M. Gaillard, A. Hicheur, Y. Karyotakis, J. P. Lees, P. Robbe, V. Tisserand, A. Zghiche Laboratoire de Physique des Particules, F-74941 Annecy-le-Vieux, France A. Palano, A. Pompili Universita di Bari, Dipartimento di Fisica and INFN, I-70126 Bari, Italy J. C. Chen, N. D. Qi, G. Rong, P. Wang, Y. S. Zhu Institute of High Energy Physics, Beijing 100039, China G. Eigen, I. Ofte, B. Stugu University of Bergen, Inst. of Physics, N-5007 Bergen, Norway G. S. Abrams, A. W. Borgland, A. B. Breon, D. N. Brown, J. Button-Shafer, R. N. Cahn, E. Charles, M. S. Gill, A. V. Gritsan, Y. Groysman, R. G. Jacobsen, R. W. Kadel, J. Kadyk, L. T. Kerth, Yu. G. Kolomensky, J. F. Kral, C. LeClerc, M. E. Levi, G. Lynch, L. M. Mir, P. J. Oddone, T. J. Orimoto, M. Pripstein, N. A. Roe, A. Romosan, M. T. Ronan, V. G. Shelkov, A. V. Telnov, W. A. Wenzel Lawrence Berkeley National Laboratory and University of California, Berkeley, CA 94720, USA T. J. Harrison, C. M. Hawkes, D. J. Knowles, S. W. O’Neale, R. C. Penny, A. T. Watson, N. K. Watson University of Birmingham, Birmingham, B15 2TT, United Kingdom T. Deppermann, K. Goetzen, H. Koch, B. Lewandowski, K. Peters, H. Schmuecker, M. Steinke Ruhr Universitat Bochum, Institut fur Experimentalphysik 1, D-44780 Bochum, Germany N. R. Barlow, W. Bhimji, J. T. Boyd, N. Chevalier, P. J. Clark, W. N. Cottingham, C. Mackay, F. F. Wilson University of Bristol, Bristol BS8 1TL, United Kingdom K. Abe, C. Hearty, T. S. Mattison, J. A. McKenna, D. Thiessen University of British Columbia, Vancouver, BC, Canada V6T 1Z1 S. Jolly, A. K. McKemey Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom V. E. Blinov, A. D. Bukin, A. R. Buzykaev, V. B. Golubev, V. N. Ivanchenko, A. A. Korol, E. A. Kravchenko, A. P. Onuchin, S. I. Serednyakov, Yu. I. Skovpen, A. N. Yushkov Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia D. Best, M. Chao, D. Kirkby, A. J. Lankford, M. Mandelkern, S. McMahon, D. P. Stoker University of California at Irvine, Irvine, CA 92697, USA C. Buchanan, S. Chun University of California at Los Angeles, Los Angeles, CA 90024, USA H. K. Hadavand, E. J. Hill, D. B. MacFarlane, H. Paar, S. Prell, Sh. Rahatlou, G. Raven, U. Schwanke, V. Sharma University of California at San Diego, La Jolla, CA 92093, USA

Measurement of the branching fraction and CP content for the decay B0 → D*+D*-

Abstract: We report a measurement of the branching fraction of the decay B^0 --> D^{*+} D^{*-} and of the CP-odd component of its final state using the BaBar detector. With data corresponding to an integrated luminosity of 20.4 fb^{-1} collected at the Upsilon(4S) resonance during 1999-2000, we have reconstructed 38 candidate signal events in the mode B^0 --> D^{*+}D^{*-} with an estimated background of 6.2 \pm 0.5 events. From these events, we determine the branching fraction to be BR(B^0 --> D^{*+}D^{*-}) = (8.3 +/- 1.6(stat) +/- 1.2(syst)) x 10^{-4}. The measured CP-odd fraction of the final state is 0.22 +/- 0.18(stat) +/- 0.03(syst).

Rare b decays to states containing a j / psi meson

Abstract: We report preliminary measurements of the branching fractions for B+ -> J/psi phi K+, B0 -> J/psi phi K0S, B0 -> J/psi phi, B0 -> J/psi eta and B -> J/psi eta' using 56 million BBbar events collected at the Y(4S) resonance with the BABAR detector at PEP-II. We measure branching fractions of B(B+ -> J/psi phi K+)=(4.4+-1.4(stat)+-0.7(syst))*10^-5 and B(B0 -> J/psi phi K0S)=(5.1+-1.9(stat)+-0.9(syst))*10^-5, and set upper limits at 90% C.L. for branching fractions, B(B -> J/\psi phi) 0.95*10^-5, B(B -> J/\psi eta) 2.7*10^-5, and B(B -> J/\psi eta') 6.4*10^-5.

Measurement of the inclusive electron spectrum in charmless semileptonic b decays near the kinematic endpoint

Abstract: A preliminary result on the study of the inclusive electron spectrum in B -> X_u e nu decays above the kinematic limit for the dominant B -> X_c e nu transitions is presented. This study is performed at the PEP-II asymmetric B Factory, where B meson pairs are produced in the decay of the Upsilon(4S) resonance. For the electron momentum range of 2.3 - 2.6 GeV/c in the Upsilon(4S) rest frame, the partial branching ratio is measured to be Delta B(B -> X_u e nu)=(0.152+-0.014+-0.014) 10^{-3}.

Evidence for the Flavor Changing Neutral Current Decays $B \to K\ell6+\ell^-$ and $B \to K*\ell^+\ell^-$

Abstract: We present preliminary results from a search for the rare, flavor-changing neutral current decays B to K l+ l- and B to K* l+ l-, where l+ l- is either an e+ e- or mu+ mu- pair. The data sample comprises (84.4 +- 0.9) X 10e6 upsilon(4S) to B B-bar decays (77.8 /fb) collected with the BaBar detector at the PEP-II B factory. For B to K l+ l-, we observe a signal with estimated significance of 4.4 sigma and obtain B(B to K l+ l-) = (0.78 +0.24 -0.20 +0.11 -0.18) X 10e-6 (averaged over l = e and mu). For B to K* l+ l-, we observe an excess of events over background with estimated significance of 2.8 sigma. We obtain B(B to K* l+ l-) = (1.68 +0.68 -0.58 +-0.28) X 10e-6 and the 90% C.L. upper limit B(B to K* l+ l-) < 3.0 X 10e-6.

Measurement of Time-Dependent $CP$ Asymmetries and the $CP$-odd Fraction in the Decay $B^0 \rightarrow D^{*+}D^{*-}$

Abstract: We present a measurement of time-dependent CP asymmetries and an updated determination of the CP-odd fraction in the decay B^0 --> D^{*+}D^{*-}. The measurements are derived from a data sample of 88 times 10^{6} B bar{B} pairs collected by the BaBar detector at the PEP-II energy asymmetric B Factory at SLAC. All results are preliminary.