Direct CP violating asymmetry in B0-->K+pi- decays

We present a measurement of the direct CP violating asymmetry in the decay B0-->K+pi(-) using a data sample of 227x10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC. We observe a total signal yield of nK-(pi(+))+nK+(pi(-))=1606+/-51 decays and measure the asymmetry (nK-(pi(+))-nK+(pi(-)))/(nK-(pi(+))+nK+(pi(-)))=-0.133+/-0.030(stat)+/-0.009(syst). The probability of observing such an asymmetry in the absence of direct CP violation is 1.3x10(-5), corresponding to 4.2 standard deviations.     

Observation of a broad structure in the pi+ pi- J/psi mass spectrum around 4.26 GeV/c2

We study initial-state radiation events, e+ e- --> gammaISR pi+ pi- J/psi, with data collected with the BABAR detector. We observe an accumulation of events near 4.26 GeV/c2 in the invariant-mass spectrum of pi+ pi- J/psi. Fits to the mass spectrum indicate that a broad resonance with a mass of about 4.26 GeV/c2 is required to describe the observed structure. The presence of additional narrow resonances cannot be excluded. The fitted width of the broad resonance is 50 to 90 MeV/c2, depending on the fit hypothesis.     

Determination of |Vub| from measurements of the electron and neutrino momenta in inclusive semileptonic B decays

We present a determination of the Cabibbo-Kobayashi-Maskawa matrix element |Vub| based on the analysis of semileptonic B decays from a sample of 88 x 10(6) Gamma(4S) decays collected with the BABAR detector at the SLAC PEP-II e+e- storage ring. Charmless semileptonic B decays are selected using measurements of the electron energy and the invariant mass squared of the electron-neutrino pair. We obtain |Vub| =(3.95 +/- 0.26(+0.58)(-0.42) +/- 0.25) x 10(-3), where the errors represent experimental uncertainties, heavy quark parameter uncertainties, and theoretical uncertainties, respectively.     

Measurement of time-dependent CP asymmetries in B0-->D(*)+/-D+/- decays

We present a first measurement of CP asymmetries in neutral B decays to D+D-, and updated CP asymmetry measurements in decays to D(*+)D- and D(*-)D+. We use fully reconstructed decays collected in a data sample of (232+/-3) x 10(6) gamma(4S)-->BB events in the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We determine the time-dependent asymmetry parameters to be SD(*+)(D-)=-0.54+/-0.35+/-0.07, CD(*+)(D-)=0.09+/-0.25+/-0.06, SD(*-)(D+)=-0.29+/-0.33+/-0.07, CD(*-)(D+)=0.17+/-0.24+/-0.04, SD+(D-)=-0.29+/-0.63+/-0.06, and CD+(D-)=0.11+/-0.35+/-0.06, where in each case the first error is statistical and the second error is systematic.     

Branching fraction and CP asymmetries of B0-->K0(S)K0(S)K0(S)

We present measurements of the branching fraction and time-dependent CP-violating asymmetries in B0-->K0(S)K0(S)K0(S) decays based on 227 x 10(6) Upsilon4S-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We obtain a branching fraction of (6.9(+0.9)(-0.8)+/-0.6) x 10(-6), and CP asymmetries C=-0.34(+0.28)(-0.25)+/-0.05 and S=-0.71(+0.38)(-0.32)+/-0.04, where the first uncertainties are statistical and the second systematic.     

Improved measurement of CP asymmetries in B0 --> (cc)K(0(*)) decays

We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 227 x 10(6) upsilon(4S) --> BB decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The amplitude of the CPasymmetry, sin2beta in the standard model, is derived from decay-time distributions from 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 B0 or B0 from its decay products. We measure sin2beta = 0.722 +/- 0.040(stat) +/- 0.023(syst) in agreement with the standard model expectation.     

Search for factorization-suppressed B-->chi(c)K(*) decays

We search for the factorization-suppressed decays B-->chi(c0)K(*) and B-->chi(c2)K(*), with chi(c0) and chi(c2) decaying into J/psi gamma, using a sample of 124 x 10(6) BB events collected with the BABAR detector at the PEP-II storage ring of the Stanford Linear Accelerator Center. We find no significant signal and set upper bounds for the branching fractions.     

Precision measurement of the weak mixing angle in Møller scattering

We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (M?ller) scattering: A(PV) = [-131 +/- 14(stat) +/- 10(syst)] x 10(-9), leading to the determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.     

Observation of a significant excess of pi0pi0 events in B meson decays

We present a study of the decay B0-->pi(0)pi(0) based on a sample of 124 x 10(6) BB pairs recorded by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We observe 46+/-13+/-3 events, where the first error is statistical and the second is systematic, corresponding to a significance of 4.2 standard deviations including systematic uncertainties. We measure the branching fraction B(B0-->pi(0)pi(0))=(2.1+/-0.6+/-0.3)x10(-6), averaged over B0 and B(0) decays.     

Limits on D0-macro D0 mixing and CP violation from the ratio of lifetimes for decay to K-pi+, K-K+, and pi- pi+

We present a measurement of D0-macro D0 mixing parameters using the ratios of lifetimes extracted from samples of D0 mesons decaying to K-pi(+), K-K+, and pi(-)pi(+). Using 91 fb(-1) of data collected by the BABAR detector at the PEP-II asymmetric-energy B Factory, we obtain a value Y=[0.8+/-0.4(stat.)(+0.5)(-0.4)(syst.)]%, which, in the limit of CP conservation, corresponds to the mixing parameter y=Delta Gamma/2 Gamma. Using the difference in lifetimes of D0 and macro D0 mesons, we obtain the CP-violation parameter Delta Y=[-0.8+/-0.6(stat.)+/-0.2(syst.)]%.