We measure the absolute branching fraction for D{sup 0}{yields}K{sup -}{pi}{sup +} using partial reconstruction of B{sup 0}{yields}D*{sup +}Xl{sup -}{nu}{sub l} decays, in which only the charged ...lepton and the pion from the decay D*{sup +}{yields}D{sup 0}{pi}{sup +} are used. Based on a data sample of 230x10{sup 6} BB pairs collected at the {upsilon}(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC, we obtain B(D{sup 0}{yields}K{sup -}{pi}{sup +})=(4.007{+-}0.037{+-}0.072)%, where the first uncertainty is statistical and the second is systematic.
Using a data sample corresponding to an integrated luminosity of 342 fb{sup -1} collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass ...energy near 10.58 GeV, we measure B({tau}{sup -}{yields}{pi}{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}}(ex.K{sub S}{sup 0}))=(8.83{+-}0.01{+-}0.13)%, B({tau}{sup -}{yields}K{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}}(ex.K{sub S}{sup 0}))=(0.273{+-}0.002{+-}0.009)%, B({tau}{sup -}{yields}K{sup -}{pi}{sup -}K{sup +}{nu}{sub {tau}})=(0.1346{+-}0.0010{+-}0.0036)%, and B({tau}{sup -}{yields}K{sup -}K{sup -}K{sup +}{nu}{sub {tau}})=(1.58{+-}0.13{+-}0.12)x10{sup -5}, where the uncertainties are statistical and systematic, respectively. These include significant improvements over previous measurements and a first measurement of B({tau}{sup -}{yields}K{sup -}K{sup -}K{sup +}{nu}{sub {tau}}) in which no resonance structure is assumed. We also report a first measurement of B({tau}{sup -}{yields}{phi}{pi}{sup -}{nu}{sub {tau}})=(3.42{+-}0.55{+-}0.25)x10{sup -5}, a new measurement of B({tau}{sup -}{yields}{phi}K{sup -}{nu}{sub {tau}})=(3.39{+-}0.20{+-}0.28)x10{sup -5} and a first upper limit on B({tau}{sup -}{yields}K{sup -}K{sup -}K{sup +}{nu}{sub {tau}}(ex.{phi}))
We report the results of a CP violation analysis of the decay B{sup {+-}}{yields}D{sub {pi}{sup +}}{sub {pi}{sup -}}{sub {pi}{sup 0}}K{sup {+-}}, where D{sub {pi}{sup +}}{sub {pi}{sup -}}{sub ...{pi}{sup 0}} indicates a neutral D meson detected in the final state {pi}{sup +}{pi}{sup -}{pi}{sup 0}, excluding K{sub S}{sup 0}{pi}{sup 0}. The analysis makes use of 324x10{sup 6} e{sup +}e{sup -}{yields}BB events recorded by the BABAR experiment at the PEP-II e{sup +}e{sup -} storage ring. Analyzing the {pi}{sup +}{pi}{sup -}{pi}{sup 0} Dalitz plot distribution and the B{sup {+-}}{yields}D{sub {pi}{sup +}}{sub {pi}{sup -}}{sub {pi}{sup 0}}K{sup {+-}} branching fraction and decay rate asymmetry, we find the following one-standard-deviation constraints on the amplitude ratio and on the weak and strong phases: 0.06<r{sub B}<0.78, -30 deg. <{gamma}<76 deg., -27 deg. <{delta}<78 deg. We also measure the magnitudes and phases of the components of the D{sup 0}{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0} decay amplitude.
We have performed a search for the flavor-changing neutral-current decays B{yields}{pi}l{sup +}l{sup -}, where l{sup +}l{sup -} is either e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -}, using a sample of ...230x10{sup 6} {upsilon}(4S){yields}BB decays collected with the BABAR detector. We observe no evidence of a signal and measure the upper limit on the isospin-averaged branching fraction to be B(B{yields}{pi}l{sup +}l{sup -})<9.1x10{sup -8} at 90% confidence level. We also search for the lepton-flavor-violating decays B{yields}{pi}e{sup {+-}}{mu}{sup {+-}} and measure an upper limit on the isospin-averaged branching fraction of B(B{yields}{pi}e{sup {+-}}{mu}{sup {+-}})<9.2x10{sup -8} at 90% confidence level.
We report observations of CP violation in the decays B{sup 0}{yields}K{sup +}{pi}{sup -} and B{sup 0}{yields}{pi}{sup +}{pi}{sup -} in a sample of 383x10{sup 6} {upsilon}(4S){yields}BB events. We ...find 4372{+-}82 B{sup 0}{yields}K{sup +}{pi}{sup -} decays and measure the direct CP-violating charge asymmetry A{sub K{pi}}=-0.107{+-}0.018(stat){sub -0.004}{sup +0.007}(syst), which excludes the CP-conserving hypothesis with a significance of 5.5 standard deviations. In the same sample, we find 1139{+-}49 B{sup 0}{yields}{pi}{sup +}{pi}{sup -} decays and measure the CP-violating asymmetries S{sub {pi}}{sub {pi}}=-0.60{+-}0.11(stat){+-}0.03(syst) and C{sub {pi}}{sub {pi}}=-0.21{+-}0.09(stat){+-}0.02(syst). CP conservation in B{sup 0}{yields}{pi}{sup +}{pi}{sup -} (S{sub {pi}}{sub {pi}}=C{sub {pi}}{sub {pi}}=0) is excluded at a confidence level 1-C.L.=8x10{sup -8}, corresponding to 5.4 standard deviations.
We report the results of a search for T, CP, and CPT violation in B{sup 0}-B{sup 0} mixing using an inclusive dilepton sample collected by the BABAR experiment at the PEP-II B factory. Using a sample ...of 232x10{sup 6} BB pairs, we measure the T and CP violation parameter |q/p|-1=(-0.8{+-}2.7(stat){+-}1.9(syst))x10{sup -3}, and the CPT and CP parameters Imz=(-13.9{+-}7.3(stat){+-}3.2(syst))x10{sup -3} and {delta}{gamma}xRez=(-7.1{+-}3.9(stat){+-}2.0(syst))x10{sup -3} ps{sup -1}. The statistical correlation between the measurements of Imz and {delta}{gamma}xRez is 76%.
We present the results of a search for the decay B{sup 0}{yields}{tau}{sup +}{tau}{sup -} in a data sample of (232{+-}3)x10{sup 6} {upsilon}(4S){yields}BB decays using the BABAR detector. Certain ...extensions of the standard model predict measurable levels of this otherwise rare decay. We reconstruct fully one neutral B meson and seek evidence for the signal decay in the rest of the event. We find no evidence for signal events and obtain B(B{sup 0}{yields}{tau}{sup +}{tau}{sup -})<4.1x10{sup -3} at the 90% confidence level.
We present the first measurement of {upsilon}(4S) decays to {pi}{sup +}{pi}{sup -}{upsilon}(1S) and {pi}{sup +}{pi}{sup -}{upsilon}(2S) based on a sample of 230x10{sup 6}{upsilon}(4S) mesons ...collected with the BABAR detector. We measure the product branching fractions B({upsilon}(4S){yields}{pi}{sup +}{pi}{sup -}{upsilon}(1S))xB({upsilon}(1S){yields}{mu}{sup +}{mu}{sup -})= =(2.23{+-}0.25{sub stat}{+-}0.27{sub syst})x10{sup -6} and B({upsilon}(4S){yields}{pi}{sup +}{pi}{sup -}{upsilon}(2S))xB({upsilon}(2S){yields}{mu}{sup +}{mu}{sup -})= =(1.69{+-}0.26{sub stat}{+-}0.20{sub syst})x10{sup -6}, from which we derive the partial widths {gamma}({upsilon}(4S){yields}{pi}{sup +}{pi}{sup -}{upsilon}(1S))=(1.8{+-}0.4) keV and {gamma}({upsilon}(4S){yields}{pi}{sup +}{pi}{sup -}{upsilon}(2S))=(2.7{+-}0.8) keV.
We present a measurement of the cross section of the process e{sup +}e{sup -}{yields}{pi}{sup +}{pi}{sup -}{psi}(2S) from threshold up to 8 GeV center-of-mass energy using events containing ...initial-state radiation, produced at the SLAC PEP-II e{sup +}e{sup -} storage rings. The study is based on 298 fb{sup -1} of data recorded with the BABAR detector. A structure is observed in the cross section not far above threshold, near 4.32 GeV. We also investigate the compatibility of this structure with the Y(4260) previously reported by this experiment.
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