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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Measurement of partial branching fractions of inclusive charmless B meson decays to K+, K-0, and pi(+). Phys. Rev. D, 83(3), 031103–8pp.
Abstract: We present measurements of partial branching fractions of B -> K+ X, B -> (KX)-X-0, and B -> pi(+) X, where X denotes any accessible final state above the endpoint for B decays to charmed mesons, specifically for momenta of the candidate hadron greater than 2.34 (2.36) GeV for kaons (pions) in the B rest frame. These measurements are sensitive to potential new-physics particles which could enter the b -> s(d) loop transitions. The analysis is performed on a data sample consisting of 383 X 10(6)B (B) over bar pairs collected with the BABAR detector at the PEP-II e(+)e(-) asymmetric energy collider. We observe the inclusive B -> pi(+) X process, and we set upper limits for B -> K+ X and B -> (KX)-X-0. Our results for these inclusive branching fractions are consistent with those of known exclusive modes, and exclude large enhancements due to sources of new physics.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2011). Measurement of the B -> D(bar)(*) D(*) K branching fractions. Phys. Rev. D, 83(3), 032004–16pp.
Abstract: We present a measurement of the branching fractions of the 22 decay channels of the B-0 and B+ mesons to (D) over bar (()*()) D-(*()) K, where the D-(*()) and (D) over bar (()*()) mesons are fully reconstructed. Summing the 10 neutral modes and the 12 charged modes, the branching fractions are found to be B(B-0 -> (D) over bar (()*()) D-(*()) K) = (3.68 +/- 0.10 +/- 0.24)% and B(B+ -> (D) over bar (()*()) D-(*()) K) = (4.05 +/- 0.11 +/- 0.28)%, where the first uncertainties are statistical and the second systematic. The results are based on 429 fb(-1) of data containing 471 X 10(6)B (B) over bar pairs collected at the Y(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory.
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BABAR Collaboration(Aubert, B. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Measurement and interpretation of moments in inclusive semileptonic decays (B)over-bar -> Xcl(nu)over-bar. Phys. Rev. D, 81(3), 032003–25pp.
Abstract: We present results for the moments of observed spectra in inclusive semileptonic B-meson decays to charm hadrons (B) over bar -> X(c)l(-)(nu) over bar. Moments of the hadronic-mass and the combined mass-and-energy spectra for different minimum electron or muon momenta between 0.8 and 1: 9 GeV/c are obtained from a sample of 232 X 10(6) Gamma(4S) -> B (B) over bar events, collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We also present a reevaluation of the moments of electron-energy spectra and partial decay fractions B((B) over bar -> X(c)e(-)(nu) over bar) for minimum electron momenta between 0.6 and 1: 5 GeV/c based on a sample of 51 X 10(6) Gamma(4S) -> B (B) over bar events. The measurements are used for the extraction of the total decay fraction, the Cabibbo-Kobayashi-Maskawa (CKM) matrix element vertical bar V-cb vertical bar, the quark masses m(b) and m(c), and four heavy-quark QCD parameters in the framework of a Heavy-Quark Expansion (HQE). We find B((B) over bar -> X(c)l(-)(nu) over bar = (10.64 +/- 0.17 +/- 0.06)% and vertical bar V-cb vertical bar = (42.05 +/- 0.45 +/- 0.70) X 10(-3).
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BABAR Collaboration(del Amo Sanchez, P. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2011). Study of B -> pi lv and B -> rho lv decays and determination of |Vub|. Phys. Rev. D, 83(3), 032007–45pp.
Abstract: We present an analysis of exclusive charmless semileptonic B-meson decays based on 377 x 10(6) B (B) over bar pairs recorded with the BABAR detector at the Y(4S) resonance. We select four event samples corresponding to the decay modes B-0 -> pi(-)l(+)v, B+ -> pi(0)l(+)v, B-0 -> rho(-)l(+)v, and B+ -> rho(0)l(+)v and find the measured branching fractions to be consistent with isospin symmetry. Assuming isospin symmetry, we combine the two B -> pi lv samples, and similarly the two B -> rho lv samples, and measure the branching fractions B(B-0 -> pi(-)l(+)v) = (1.41 +/- 0.05 +/- 0.07) x 10(-4) and B(B-0 -> rho(-)l(+)v) = (1.75 +/- 0.15 +/- 0.27) x 10(-4), where the errors are statistical and systematic. We compare the measured distribution in q(2), the momentum transfer squared, with predictions for the form factors from QCD calculations and determine the Cabibbo-Kobayashi-Maskawa matrix element vertical bar V-ub vertical bar. Based on the measured partial branching fraction for B -> pi lv in the range q(2) < 12 GeV2 and the most recent QCD light-cone sum-rule calculations, we obtain vertical bar V-ub vertical bar = (3.78 +/- 0.13(-0.40)(+0.55)10(-3), where the errors refer to the experimental and theoretical uncertainties. From a simultaneous fit to the data over the full q(2) range and the FNAL/MILC lattice QCD results, we obtain vertical bar V-ub vertical bar = (2.95 +/- 0.31) x 10(-3) from B -> pi lv, where the error is the combined experimental and theoretical uncertainty.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2011). Studies of tau(-) -> eta K- nu(tau) and tau(-) -> eta pi(-) nu(tau) at BABAR and a search for a second-class current. Phys. Rev. D, 83(3), 032002–10pp.
Abstract: We report on analyses of tau lepton decays tau(-) -> eta K- nu(tau) and tau(-) -> eta pi(-) nu(tau), with eta -> pi(+) pi(-) pi(0), using 470 fb(-1) of data from the BABAR experiment at PEP-II, collected at center-of-mass energies at and near the Y(4S) resonance. We measure the branching fraction for the tau(-) -> eta K- nu(tau) decay mode, B(tau(-) -> eta K- nu(tau)) = (1.42 +/- 0.11(stat) +/- 0.07(syst)) x 10(-4), and report a 95% confidence level upper limit for the second-class current process tau(-) -> eta pi(-) nu(tau), B(tau(-) -> eta pi(-) nu(tau)) < 9.9 x 10(-5).
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2011). Search for CP violation using T-odd correlations in D(+) -> K(+)K(S)(0) pi(+)pi(-) and D(s)(+) -> K(+)K(S)(0) pi(+)pi(-) decays. Phys. Rev. D, 84(3), 031103–9pp.
Abstract: We search for CP violation in a sample of 20 000 Cabibbo-suppressed decays, D(+) -> K(+)K(S)(0)pi(+)pi(-), and 30 000 Cabibbo-favored decays, D(+) -> K(+)K(S)(0)pi(+)pi(-). We use 520 fb(-1) of data recorded by the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider operating at center of mass energies near 10.6 GeV. We search for CP violation in the difference between the T-odd asymmetries obtained using triple product correlations of the D(+)(D(s)(+)) and D(-)(D(s)(-)) decays, respectively. The T violation parameter values obtained are A(T)(D(+)) = (-12.0 +/- 10.0(stat) +/- 4.6(syst)) x 10(-3) and A(T)(D(s)(+)) = (-13.6 +/- 7.7(stat) +/- 3.4(syst)) x 10(-3), which are consistent with the standard model expectations.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Search for CP violation in the decay tau(-) -> pi K-(s)0 (>= 0 pi(0))v(tau). Phys. Rev. D, 85(3), 031102–8pp.
Abstract: We report a search for CP violation in the decay tau(-) -> pi K--(s)0 (>= 0 pi(0))v(tau) using a data set of 437 x 10(6) tau-lepton pairs, corresponding to an integrated luminosity of 476 fb(-1), collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) storage rings. The CP-violating decay-rate asymmetry is determined to be (-0.36 +/- 0.23 +/- 0.11)% approximately 2.8 standard deviations from the standard model prediction of (0.36 +/- 0.01)%.
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BABAR Collaboration(Lees, J. P. et al), Azzolini, V., Martinez-Vidal, F., & Oyanguren, A. (2012). Study of (B)over-bar -> X(u)l(v)over-bar decays in B(B)over-bar events tagged by a fully reconstructed B-meson decay and determination of vertical bar V-ub vertical bar. Phys. Rev. D, 86(3), 032004–23pp.
Abstract: We report measurements of partial branching fractions for inclusive charmless semileptonic B decays (B) over bar -> X(u)l (v) over bar and the determination of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element vertical bar V-ub vertical bar. The analysis is based on a sample of 467 x 10(6) Y(4S) -> B (B) over bar decays recorded with the BABAR detector at the PEP- II e(+)e(-) storage rings. We select events in which the decay of one of the B mesons is fully reconstructed and an electron or a muon signals the semileptonic decay of the other B meson. We measure partial branching fractions Delta B in several restricted regions of phase space and determine the CKM element vertical bar V-ub vertical bar based on different QCD predictions. For decays with a charged lepton momentum p(l)* > 1.0 GeV in the B meson rest frame, we obtain Delta B = (1.80 +/- 0.13(stat) +/- 0.15(sys) +/- 0.02(theo)) x 10(-3) from a fit to the two-dimensional M-X – q(2) distribution. Here, M-X refers to the invariant mass of the final state hadron X and q(2) is the invariant mass squared of the charged lepton and neutrino. From this measurement we extract vertical bar V-ub vertical bar = (4.33 +/- 0.24(exp) +/- 0.15(theo)) x 10(-3) as the arithmetic average of four results obtained from four different QCD predictions of the partial rate. We separately determine partial branching fractions for (B) over bar (0) and B- decays and derive a limit on the isospin breaking in (B) over bar -> X(u)l (v) over bar decays.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Search for the decay modes D-0 -> e(+) e(-), D-0 -> mu(+) mu(-), and D-0 -> e(+/-) μ-/+. Phys. Rev. D, 86(3), 032001–10pp.
Abstract: We present searches for the rare decay modes D-0 -> e(+) e(-), D-0 -> mu(+) mu(-), and D-0 -> e(+/-) mu(-/+) in continuum e(+) e(-) -> c (c) over bar events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468 fb(-1). These decays are highly Glashow-Iliopoulos-Maiani suppressed but may be enhanced in several extensions of the standard model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D-0 -> mu(+) mu(-) channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the Feldman-Cousins method, we set the following 90% confidence level intervals on the branching fractions: B(D-0 -> e(+) e(-)) < 1.7 x 10(-7), B(D-0 -> mu(+) mu(-)) within [0.6,8.1] x 10(-7), and B(D-0 -> e(+/-) mu(-/+)) < 3.3 x 10(-7).
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Precise measurement of the e(+)e(-) -> pi(+)pi(-)(gamma) cross section with the initial-state radiation method at BABAR. Phys. Rev. D, 86(3), 032013–49pp.
Abstract: A precise measurement of the cross section of the process e(+)e(-) -> pi(+)pi(-) (gamma) from threshold to an energy of 3 GeV is obtained with the initial-state radiation (ISR) method using 232 fb(-1) of data collected with the BABAR detector at e(+)e(-) center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e(+)e(-) -> mu(+)mu(-) (gamma)gamma(ISR), which is found to agree with the next-to-leading-order QED prediction to within 1.1%. The cross section for the process e(+)e(-) -> pi(+)pi(-) (gamma) is obtained with a systematic uncertainty of 0.5% in the dominant rho resonance region. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured pi pi cross section from threshold to 1.8 GeV is (514.1 +/- 2.2(stat) +/- 3.1(sys)) x 10(-10).
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