Dalitz Plot Analysis of D0 Hadronic Decays D0 -> K0K-pi+, D0 -> K0barK+pi- and D0 -> K0barK+K-

A Dalitz plot analysis of the D0 hadronic decays D0 -> K0 K- pi+, D0 -> K0bar K+ pi- and D0 -> K0bar K+ K- is presented. This analysis is based on a data sample of 22 fb-1 collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC running on or near the Y(4S) resonance. The events are selected from continuum e+ e- annihilations using the decay D*+ -> D0 pi+. Preliminary measurements of the branching fractions of the above hadronic decays are obtained. Preliminary estimates of fractions and phases for resonant and nonresonant contributions to the Dalitz plot are also presented.Comment: 23 pages, 10 figures, 7 tables; submitted to ICHEP200

Measurement of the B0 --> pi- l+ nu and B+ --> pi0 l+ nu Branching Fractions and Determination of |V_ub| in Y(4S) Events Tagged by a Fully Reconstructed B Meson

We report preliminary measurements of the charmless exclusive semileptonic branching fractions of the B0 --> pi- l+ nu and B+ --> pi0 l+ nu decays, based on 211 fb-1 of data collected at the Y(4S) resonance by the BABAR detector. In events in which the decay of one B meson to a hadronic final state is fully reconstructed, the semileptonic decay of the second B meson is identified by the detection of a charged lepton and a pion. We measure the partial branching fractions for B0 --> pi- l+ nu and B+ --> pi0 l+ nu in three regions of the invariant mass squared of the lepton pair, and we obtain the total branching fractions BF(B0 --> pi- l+ nu) = (1.14 +/- 0.27(stat) +/- 0.17(syst)) x 10^-4 and BF(B+ --> pi0 l+ nu) = (0.86 +/- 0.22(stat) +/- 0.11(syst)) x 10^-4. Using isospin symmetry, we measure the combined total branching fraction BF(B0 --> pi- l+ nu) = (1.28 +/- 0.23(stat) +/- 0.16(syst)) x 10^-4. Theoretical predictions of the form-factor are used to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |V_ub| = (3.7 +/- 0.3(stat) +/- 0.2(syst) +0.8-0.5(FF)) x 10^-3, where the last error is due to the form-factor normalization.Comment: 20 pages, 11 postscript figures, submitted to HEP 200

Improved Measurements of Branching Fractions for B0 -> pi+pi-, K+pi-, and Search for K+K- at BaBar

We present preliminary measurements of branching fractions for the charmless two-body decays B0 -> pi+pi- and K+pi-, and a search for B0 -> K+K- using a data sample of approximately 227 million BBbar decays. Signal yields are extracted with a multi-dimensional maximum likelihood fit, and the efficiency is corrected for the effects of final-state radiation. We find the charge-averaged branching fractions (in units of 10^{-6}): Br(B0 -> pi+pi-) = 5.5 +- 0.4 +- 0.3, Br(B0 -> K+pi-) = 19.2 +- 0.6 +- 0.6, Br(B0 -> K+K-) = < 0.40. The errors are statistical followed by systematic, and the upper limit on K+K- represents a confidence level of 90%.Comment: 15 pages, 12 postscript figues, presented at EPS 200

Measurement of CP-Violating Asymmetries in the B0->K+K-K0 Dalitz Plot

We present a preliminary measurement of CP-violation parameters in the decay B0 -> K+K-K0, using approximately 347 million BBbar events collected by the BABAR detector at SLAC. Reconstructing the neutral kaon as KS -> pi+pi-, KS -> pi0pi0, or KL, we analyze the Dalitz plot distribution and measure fractions to intermediate states. We extract CP parameters from the asymmetries in amplitudes and phases between B0 and B0bar decays across the Dalitz plot. For decays to phiK0, we find beta_eff=0.06 +/- 0.16 +/- 0.05, Acp=-0.18 +/- 0.20 +/- 0.10, where the first uncertainty is statistical and the second one is systematic. For decays to f0K0, we find beta_eff=0.18 +/- 0.19 +/- 0.04, Acp=0.45 +/- 0.28 +/- 0.10. Combining all KKK0 events and taking account of the different CP eigenvalues of the individual Dalitz plot components, we find beta_eff = 0.361 +/- 0.079 +/- 0.037, Acp = -0.034 +/- 0.079 +/- 0.025. The trigonometric reflection at pi/2 - beta_eff is disfavored at 4.6 sigma. We also study angular distributions in B0 -> K+K-KS and B+ -> phi K+ decays and measure the direct CP asymmetry in B+ -> phi K+ decays, Acp = 0.046 +/- 0.046 +/- 0.017.Comment: 27 pages, 10 figures, contributed to ICHEP0

Time-dependent Dalitz Plot Analysis of B0 --> Ks pi+ pi-

We perform a time-dependent Dalitz plot analysis of $B^0 \to K^0_{\scriptscriptstyle S}\pi^+\pi^-$ in order to extract the ${CP}$ violation parameters of $f_0(980) K^0_{\scriptscriptstyle S}$ and $\rho^0(770) K^0_{\scriptscriptstyle S}$ and direct ${CP}$-asymmetries of $K^{*+}(892) \pi^-$. The results are obtained from a data sample of $(383\pm3)\times10^{6}$ $B \bar{B}$ decays, collected with the BaBar detector at the PEP2 asymmetric--energy $B$ factory at SLAC. The measured values of $2\beta_{\rm eff}$ in $B^0$ decays to $f_0(980)K^0_{\scriptscriptstyle S}$ and $\rho^0(770) K^0_{\scriptscriptstyle S}$ are $(89^{+22}_{-20} \pm 5 \pm 8)^\circ$ and $(37 ^{+19}_{-17} \pm 5 \pm 6)^\circ$, respectively, where the first quoted uncertainty is statistical, the second is systematic and the third is Dalitz plot signal model uncertainty. We measure the significance of $2\beta_{\rm eff}(f_0(980)K^0_{\scriptscriptstyle S})\neq 0$ to be $4.3 \sigma$. In decays to $K^*(892) \pi$ we find $A_{{CP}} = -0.18 \pm 0.10 \pm 0.03 \pm 0.03$. The measured phase difference between the decay amplitudes of $B^0 \to K^{*+}(892) \pi^-$ and $\bar{B}^0 \to K^{*-}(892) \pi^+$ is $(-164 \pm 24 \pm 12 \pm 15)^\circ$. All results are preliminary.Comment: 29 pages, 19 postscript figures, submitted to Lepton-Photon 200

A Search for the Rare Decay B0 --> D_S+ rho-

We report on a search for the decay B0 --> D_S+ rho- in a sample of 90 million Y(4S) decays into B meson pairs collected between 1999 and 2001 with the BaBar detector at the PEP-II asymmetric-energy e+e- collider. No significant excess of signal events above the expected background is observed. We set a 90% C.L. limit on the branching fraction Br(B0 --> D_S+ rho-)< 1.9*10^{-5}. Assuming a flavor SU(3) symmetry relation between the decays B0 --> D_S+ rho- and B0 --> D+ rho-, we set a limit on the ratio of CKM-suppressed to CKM-favored amplitudes r(D rho)<9.5*10^{-3} at 90% C.L. All results are preliminary.Comment: 16 pages, 8 postscript figues, submitted to ICHEP200

Exclusive B decays to charmonium final states

We report on exclusive decays of B mesons into final states containing charmonium using data collected with the BABAR detector at the PEP-II storage rings. The charmonium states considered here are J/psi, psi(2S), and chi_C1. Branching fractions for several exclusive final states, a measurement of the decay amplitudes for the B0 --> J/psi K* decay, and measurements of the B0 and B+ masses are presented. All of the results we present here are preliminary.Comment: 18 pages, 7 postscript figures, contributed paper to ICHEP200

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^-6Comment: 12 pages, 2 postscript figures, Contributed to the XXI International Symposium on Lepton and Photon Interactions at High Energies, 8/11 - 8/16/2003, Fermilab, Illinois US

Measurement of the Inclusive Electron Spectrum in Charmless Semileptonic B Decays Near the Kinematic Endpoint

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}.Comment: 17 pages, 3 postscript figures, submitted to ICHEP200

Measurement of the B --> Xs l+ l- Branching Fraction Using a Sum over Exclusive Modes

We present a measurement of the branching fraction for the flavor-changing neutral current process B --> Xs l+ l- based on a sample of 88.9 \times 10^6 Upsilon(4S) --> BBbar events recorded with the BaBar detector at the PEP-II e+e- storage ring. The final state is reconstructed from pairs of electrons or muons and a hadronic system consisting of one K+/- or K0s and up to two pions, with at most one pi0. Summing over both lepton flavors, we observe a signal of 41 +/- 10(stat) +/- 2(syst) events with a statistical significance of 4.6 sigmas. The inclusive branching fraction is determined to be BF(B --> Xs l+ l-) = [6.3 +/- 1.6(stat) +1.8 -1.5(syst)] 10^{-6} for m(l+ l-) > 0.2 GeV/c^2. All results are preliminary.Comment: 18 pages, 3 postscript figures, contributed to Lepton-Photon 200