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Observation of the Inclusive D^{* -} Production in the Decay of Y(1S)

Description: The authors present a study of the inclusive D*{sup {+-}} production in the decay of {Upsilon}(1S) using (98.6 {+-} 0.9) x 10{sup 6} {Upsilon}(2S) mesons collected with the BABAR detector at the {Upsilon}(2S) resonance. Using the decay chain {Upsilon}(2S) {yields} {pi}{sup +}{pi}{sup -}{Upsilon}(1S), {Upsilon}(1S) {yields} D*{sup {+-}}X, where X is unobserved, they measure the branching fraction {Beta}[{Upsilon}(1S) {yields} D*{sup {+-}}X] = (2.52 {+-} 0.13(stat) {+-} 0.15(syst))% and the D*{sup {+-}} momentum distribution in the rest frame of the {Upsilon}(1S). They find evidence for an excess of D*{sup {+-}} production over the expected rate from the virtual photon annihilation process {Upsilon}(1S) {yields} {gamma}* {yields} c{bar c} {yields} D*{sup {+-}} X.
Date: December 17, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

Observation and Polarization of B->phiK1+ and phiK*2+

Description: With the full BABAR data sample of 465 million B{bar B} pairs, they observe the decays B{sup {+-}} {yields} {psi}K{sub 1}(1270){sup {+-}} and B{sup {+-}} {yields} {psi}K*{sub 2}(1430){sup {+-}}. They measure the branching fractions (6.1 {+-} 1.6 {+-} 1.1) x 10{sup -6} and (8.4 {+-} 1.9 {+-} 0.9) x 10{sup -6} and the fractions of longitudinal polarization 0.46{sub -0.13-0.07}{sup +0.12+0.03} and 0.80{sub -0.10}{sup +0.09} {+-} 0.03, respectively. They also report on the B{sup {+-}} {yields} {psi}K*{sub 0}(1430){sup {+-}} decay branching fraction of (7.0 {+-} 1.3 {+-} 0.9) x 10{sup -6} and several parameters sensitive to CP violation and interference in the above three decays. Upper limits are placed on the B{sup {+-}} decay rates to final states with {psi} and K{sub 1}(1400){sup {+-}}, K*(1410){sup {+-}}, K{sub 2}(1770){sup {+-}}, or K{sub 2}(1820){sup {+-}}. Understanding the observed polarization pattern requires amplitude contributions from an uncertain source.
Date: October 31, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Direct CP, Lepton Flavor and Isospin Asymmetries in the Decays B->K(*)l+l-

Description: We measure rate asymmetries for the rare decays B {yields} K{sup (*)}{ell}{sup +}{ell}{sup -}, where {ell}{sup +}{ell}{sup -} is either e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -}, using a sample of 384 million B{bar B} events collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider. We find no evidence for direct CP or lepton-flavor asymmetries. For dilepton masses below the J/{psi} resonance, we find evidence for unexpectedly large isospin asymmetries in both B {yields} K{ell}{sup +}{ell}{sup -} and B {yields} K*{ell}{sup +}{ell}{sup -} which differ respectively by 3.2{sigma} and 2.7{sigma}, including systematic uncertainties, from the Standard Model expectations.
Date: March 3, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

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

Description: We present new measurements of time-dependent CP asymmetries for B{sup 0} {yields} D{sup (*)+}d{sup (*)-} decays using (467 {+-} 5) x 10{sup 6} B{bar B} pairs collected with the BABAR detector located at the PEP-II B Factory at the Stanford Linear Accelerator Center. We determine the CP-odd fraction of the B{sup 0} {yields} D*{sup +}D*{sup -} decays to be R{perpendicular} = 0.158 {+-} 0.028 {+-} 0.006 and find CP asymmetry parameters for the CP-even component of the decay S{sub +} = -0.76 {+-} 0.16 {+-} 0.04 and C{sub +} = 0.00 {+-} 0.12 {+-} 0.02. We measure S = -0.63{+-}0.36{+-}0.05 and C = -0.07{+-}0.23{+-}0.03 for B{sup 0} {yields} D{sup +}D{sup -}, S = -0.62{+-}0.21{+-}0.03 and C = 0.08 {+-} 0.17 {+-} 0.04 for B{sup 0} {yields} D*{sup +}D{sup -}, and S = -0.73 {+-} 0.23 {+-} 0.05 and C = 0.00 {+-} 0.17 {+-} 0.03 for B{sup 0} {yields} D{sup +}D*{sup -}. For the B{sup 0} {yields} D*{sup {+-}}D{sup {-+}} decays, we also determine the CP-violating asymmetry A = 0.008 {+-} 0.048 {+-} 0.013. In each case, the first uncertainty is statistical and the second is systematic. The measured values for the asymmetries are all consistent with the Standard Model.
Date: February 12, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Search for Lepton Flavour Violating Decays tau- to l- Ks with the BaBar experiment

Description: A search for the lepton flavor violating decays {tau}{sup -} {yields} l{sup -} K{sub S}{sup 0} (l = e or {mu}) has been performed using a data sample corresponding to an integrated luminosity of 469 fb{sup -1}, collected with the BABAR detector at the SLAC PEP-II e{sup +}e{sup -} asymmetric energy collider. No statistically significant signal has been observed in either channel and the estimated upper limits on branching fractions are {Beta}({tau}{sup -} {yields} e{sup -} K{sub S}{sup 0}) < 3.3 x 10{sup -8} and {Beta}({tau}{sup -} {yields} {mu}{sup -}K{sub S}{sup 0}) < 4.0 x 10{sup -8} at 90% confidence level.
Date: January 6, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Search for the decay B^+ \to K_S^0 K_S^0 \pi ^+

Description: The authors search for charmless decays of charged B mesons to the three-body final state K{sub S}{sup 0}K{sub S}{sup 0}{pi}{sup +}. Using a data sample of 423.7 fb{sup -1} collected at the {Upsilon}(4S) resonance with the BABAR detector, corresponding to (465.1 {+-} 5.1) x 10{sup 6} B{bar B} pairs, they find no significant signal and determine a 90% confidence level upper limit on the branching fraction of 5.1 x 10{sup -7}.
Date: February 23, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Dalitz Plot Analysis of Ds+->pi+pi-pi+

Description: A Dalitz plot analysis of {approx} 13, 000 D{sub s}{sup +} decays to {pi}{sup +}{pi}{sup +}{pi}{sup -} has been performed. A 384 fb{sup -1} data sample, recorded by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage ring running at center of mass energies near 10.6 GeV, is used. Amplitudes and phases of the intermediate resonances which contribute to this final state are measured. A high precision measurement of the ratio: {Beta}(D{sub s}{sup +} {yields} {pi}{sup +}{pi}{sup +}{pi}{sup -})/{Beta}(D{sub s}{sup +} {yields} K{sup +}K{sup -}{pi}{sup +}) = 0.199 {+-} 0.004 {+-} 0.006 is performed. Using a model independent partial wave analysis the amplitude and phase of the S-wave have been measured.
Date: January 26, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Measurements of B to {pi, eta, eta'} l nu Branching Fractions andDetermination of |Vub| with Semileptonically Tagged B Mesons

Description: The authors report measurements of branching fractions for the decays B {yields} P{ell}{nu}{sub {ell}}, where P are the pseudoscalar charmless mesons {pi}{sup -}, {pi}{sup 0}, {eta} and {eta}{prime}, based on 348 fb{sup -1} of data collected with the BABAR detector, using B{sup 0} and B{sup +} mesons found in the recoil of a second B meson decaying as B {yields} D{sup (*)}{ell}{nu}{sub {ell}}. Assuming isospin symmetry, they combine pionic branching fractions to obtain {Beta}(B{sup 0} {yields} {pi}{sup -} {ell}{sup +} {nu}{sub {ell}}) = (1.54 {+-} 0.17{sub (stat)} {+-} 0.09{sub (syst)}) x 10{sup -4}; they find 3.2{sigma} evidence of the decay B{sup +} {yields} {eta}{ell}{sup +}{nu}{sub {ell}} and measure its branching fraction to be (0.64 {+-} 0.20{sub (stat)} {+-} 0.3{sub (syst)}) x 10{sup -4}, and determine {Beta}(B{sup +} {yields} {eta}{prime}{ell}{sup +}{nu}{sub {ell}}) < 0.47 x 10{sup -4} to 90% confidence level. Using partial branching fractions for the pionic decays in ranges of the momentum transfer and a recent form factor calculation, they obtain the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |V{sub ub}| = (4.0 {+-} 0.5{sub (stat)} {+-} 0.2{sub (syst){sub -0.5}{sup +0.7}(theory)}) x 10{sup -3}.
Date: June 2, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Search for b\to u Transitions in \Bz \to \Dz \Kstarz Decays

Description: We present a study of the decays B{sup 0} {yields} D{sup 0} K*{sup 0} and B{sup 0} {yields} {bar D}{sup 0} K*{sup 0} with K*{sup 0} {yields} K{sup +}{pi}{sup -}. The D{sup 0} and the {bar D}{sup 0} mesons are reconstructed in the final states f = K{sup +} {pi}{sup -}, K{sup +}{pi}{sup -}{pi}{sup 0}, K{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} and their charge conjugates. Using a sample of 465 million B{bar B} pairs collected with the BABAR detector at PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC, we measure the ratio R{sub ADS} {triple_bond} [{Lambda}({bar B}{sup 0} {yields} [f]{sub D}{bar K}*{sup 0}) + {Lambda}(B{sup 0} {yields} [{bar f}]{sub D}K*{sup 0})]/[{Lambda}({bar B}{sup 0} {yields} [{bar f}]{sub D}{bar K}*{sup 0}) + {Lambda}(B{sup 0} {yields} [f]{sub D}K*{sup 0})] for the three final states. We do not find significant evidence for a signal and set the following limits at 95% probability: R{sub ADS}(K{pi}) < 0.244, R{sub ADS}(K{pi}{pi}{sup 0}) < 0.181 and R{sub ADS}(K{pi}{pi}{pi}) < 0.391. From the combination of these three results, we find that the ratio r{sub S} between the b {yields} u and the b {yields} c amplitudes lies in the range [0.07; 0.41] at 95% probability.
Date: April 13, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Evidence for B+ -> K*0bar K*+

Description: We present measurements of the branching fraction and fraction of longitudinal polarization for the decay B{sup +} {yields} {bar K}*{sup 0} K*{sup +} with a sample of 467 {+-} 5 million B{bar B} pairs collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. We obtain the branching fraction {Beta}(B{sup +} {yields} {bar K}*{sup 0} K*{sup +}) = (1.2 {+-} 0.5 {+-} 0.1) x 10{sup ?6} with a significance of 3.7 standard deviations including systematic uncertainties. We measure the fraction of longitudinal polarization f{sub L} = 0.75{sub -0.26}{sup +0.16} {+-} 0.03. The first error quoted is statistical and the second is systematic.
Date: June 19, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Search for the Rare Leptonic Decays B^+ \to l^+ \nu_l (l=e,\mu)

Description: We have performed a search for the rare leptonic decays B{sup +} {yields} {ell}{sup +} {nu}{sub {ell}}({ell} = e,{mu}), using data collected at the ?(4S) resonance by the BABAR detector at the PEP-II storage ring. In a sample of 468 x 10{sup 6} B{bar B} pairs we find no evidence for a signal and set an upper limit on the branching fractions B(B{sup +} {yields} e{sup +}{nu}{sub e}) < 1.9 x 10{sup -6} at the 90% confidence level, using a Bayesian approach.
Date: June 19, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the e^+e^-\to b\bar{b} cross section between \SqrtS=10.54 and 11.20 \gev

Description: We report e{sup +}e{sup -} {yields} b{bar b} cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the PEP-II e{sup +}e{sup -} collider. A total relative error of about 5% is reached in more than three hundred center-of-mass energy steps, separated by about 5MeV. These measurements can be used to derive precise information on the parameters of the {Upsilon}(10860) and {Upsilon}(11020) resonances. In particular we show that their widths may be smaller than previously measured.
Date: June 19, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Observation of the baryonic B-decay B0bar -> LambdaC antiproton K- pi

Description: The authors report the observation of the baryonic B-decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}K{sup -}{pi}{sup +}, excluding contributions from the decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar {Lambda}}K{sup -}. Using a data sample of 467 million B{bar B} pairs collected with the BABAR detector at the PEP-II storage ring at SLAC, the measured branching fraction is (4.33 {+-} 0.82){sub stat} {+-} 0.33{sub syst} {+-} 1.13{sub {Lambda}{sub c}{sup +}} x 10{sup -5}. In addition they find evidence for the resonant decay {bar B}{sup 0} {yields} {Sigma}{sub c}(2455){sup ++}{bar p}K{sup -} and determine its branching fraction to be (1.11 {+-} 0.30{sub stat} {+-} 0.09{sub syst} {+-} 0.29{sub {Lambda}{sub c}{sup +}}) x 10{sup -5}. The errors are statistical, systematic, and due to the uncertainty in the {Lambda}{sub c}{sup +} branching fraction. For the resonant decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}{bar K}*{sup 0} we obtain an upper limit of 2.42 x 10{sup -5} at 90% confidence level.
Date: October 20, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

Measurement of D0-D0bar Mixing using the Ratio of D0->K-pi and K-K Lifetimes

Description: We measure the rate of D{sup 0}-{bar D}{sup 0} mixing with the observable y{sub CP} = ({tau}{sub K{pi}}/{tau}{sub KK}) - 1, where {tau}{sub KK} and {tau}{sub K{pi}} are respectively the mean lifetimes of CP-even D{sup 0} {yields} K{sup +}K{sup -} and CP-mixed D{sup 0} {yields} K{sup -}{pi}{sup +} decays, using a data sample of 384 fb{sup -1} collected by the BABAR detector at the SLAC PEP-II asymmetric-energy B Factory. From a sample of D{sup 0} and {bar D}{sup 0} decays where the initial flavor of the decaying meson is not determined, we obtain y{sub CP} = [1.12 {+-} 0.26(stat) {+-} 0.22(syst)]%, which excludes the no-mixing hypothesis at 3.3{sigma}, including both statistical and systematic uncertainties. This result is in good agreement with a previous BABAR measurement of y{sub CP} obtained from a sample of D*{sup +} {yields} D{sup 0}{pi}{sup +} events, where the D{sup 0} decays to K{sup -}{pi}{sup +}, K{sup +}K{sup -}, and {pi}{sup +}{pi}{sup -}, which is disjoint with the untagged D{sup 0} events used here. Combining the two results taking into account statistical and systematic uncertainties, where the systematic uncertainties are assumed to be 100% correlated, we find y{sub CP} = [1.16 {+-} 0.22(stat) {+-} 0.18(syst)]%, which excludes the no-mixing hypothesis at 4.1{sigma}.
Date: October 17, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the Branching Fraction and Lambda-bar Polarization in B0 -> Lambda-par p pi-

Description: We present a measurement of the B{sup 0} {yields} {bar {Lambda}}p{pi}{sup -} branching fraction performed using the BABAR detector at the PEP-II asymmetric e{sup +}e{sup -} collider. Based on a sample of 467 x 10{sup 6} B{bar B} pairs we measure {Beta}(B{sup 0} {yields} {bar {Lambda}}p{pi}{sup -}) [3.07 {+-} 0.31(stat.) {+-} 0.23(syst.)] x 10{sup -6}. The measured differential spectrum as a function of the dibaryon invariant mass m({bar {Lambda}}p) shows a near-threshold enhancement similar to that observed in other baryonic B decays. We study the {bar {Lambda}} polarization as a function of {bar {Lambda}} energy in the B{sup 0} rest frame (E*{sub {bar {Lambda}}}) and compare it with theoretical expectations of fully longitudinally right-polarized {bar {Lambda}} at large E*{sub {bar {Lambda}}}.
Date: August 3, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

Search for the B to K nu nu-bar Decay Using Semi-Leptonic Tags

Description: We present an update of the search for the flavor-changing neutral current B{sup +} {yields} K{sup +}{nu}{bar {nu}} decay using 351 X 10{sup 6} B{bar B} pairs collected at the {Upsilon}(4S) resonance with the BABAR detector at the SLAC PEP-II B factory. Due to the presence of two neutrinos in the final state, we require the reconstruction of the companion B in the event through the decay channel B{sup -} {yields} D{sup 0}{ell}{sup -}{bar {nu}}X. We find 38 candidates in the data with an expected background of 31{-+} 12. This allows us to set an upper limit on the branching fraction for B{sup +} {yields} K{sup +}{nu}{bar {nu}} of 4.5 X 10{sup -5} at 90% confidence level.
Date: June 2, 2010
Creator: Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department