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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2012). Observation and study of the baryonic B-meson decays B -> D(*) p(p)over-bar (pi)(pi). Phys. Rev. D, 85(9), 092017–21pp.
Abstract: We present results for B-meson decay modes involving a charm meson, protons, and pions using 455 x 10(6) B (B) over bar pairs recorded by the BaBar detector at the SLAC PEP-II asymmetric-energy e(+)e(-) collider. The branching fractions are measured for the following ten decays: (B) over bar (0) -> D-0 p (p) over bar, (B) over bar (0) -> D*(0) p (p) over bar, (B) over bar (0) -> D+ p (p) over bar pi(-) , (B) over bar (0) -> D-0 p (p) over bar pi(-) , B- -> D-0 p (p) over bar pi(-) , B- -> D*(0) p (p) over bar pi(-) , (B) over bar (0) -> D-0 p (p) over bar pi(-) pi(+) , (B) over bar (0) -> D*(0) p (p) over bar pi(-) pi(+) B- -> D+ p (p) over bar pi(-) pi(-) , and B- -> D*(0) p (p) over bar pi(-) pi(-). The four B- and the two five-body (B) over bar (0) modes are observed for the first time. The four-body modes are enhanced compared to the three- and the five-body modes. In the three-body modes, the M(p (p) over bar) and M(D-(*)0 p) invariant- mass distributions show enhancements near threshold values. In the four-body mode (B) over bar (0) -> D+ p (p) over bar pi(-) , the M(p pi(-)) distribution shows a narrow structure of unknown origin near 1: 5 GeV/c(2). The distributions for the five-body modes, in contrast to the others, are similar to the expectations from uniform phase-space predictions.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Measurement of D-0-(D)over-bar(0) Mixing Parameters Using D-0 -> K-S(0)pi(+) pi(-) and D-0 -> (KSK+K-)-K-0 Decays. Phys. Rev. Lett., 105(8), 081803–7pp.
Abstract: We report a direct measurement of D-0-(D) over bar (0) mixing parameters through a time-dependent amplitude analysis of the Dalitz plots of D-0 -> K-S(0)pi(+)pi(-) and, for the first time, D-0 -> (KSK+K-)-K-0 decays. The low-momentum pion pi(+)(s) in the decay D*(+) -> D-0 pi(+)(s) identifies the flavor of the neutral D meson at its production. Using 468.5 fb(-1) of e(+)e(-) colliding-beam data recorded near root s = 10.6 by the BABAR detector at the PEP-II asymmetric-energy collider at SLAC, we measure the mixing parameters x = [1.6 + 2.3(stat) +/- 1.2(syst) +/- 0.8(model)] X 10(-3), and y = [5.7 +/- 2.0(stat) +/- 1.3(syst) +/- 0.7(model)] X 10(-3). These results provide the best measurement to date of x and y. The knowledge of the value of x, in particular, is crucial for understanding the origin of mixing.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Search for B+ -> (D+K0) and B+ -> (D+K0) decays. Phys. Rev. D, 82(9), 092006–11pp.
Abstract: We report a search for the rare decays B+ -> (D+K0) and B+ -> D+K*(0) in an event sample of approximately 465 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC National Accelerator Laboratory. We find no significant evidence for either mode and we set 90% probability upper limits on the branching fractions of B(B+ -> (D+K0)) < 2.9 x 10(-6) and B(B+ -> D+K*(0)) < 3.0 x 10(-6)
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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. (2010). Observation of the rare decay B-0 -> K-S(0) K-+/-pi(-/+). Phys. Rev. D, 82(3), 031101–8pp.
Abstract: We report an analysis of charmless hadronic decays of neutral B mesons to the final state (KSK +/-)-K-0 pi(-/+) (sic), using a data sample of (465 +/- 5) x 10(6) B (B) over bar events collected with the BABAR detector at the Gamma(4S) resonance. We observe an excess of signal events with a significance of 5.2 standard deviations including systematic uncertainties and measure the branching fraction to be B(B-0 -> (KSK +/-)-K-0 pi(-/+) (sic) (3.2 +/- 0.5 +/- 0.3) x 10(-6), where the uncertainties are statistical and systematic, respectively.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Search for CP violation in the decay D(+/-) --> K_S pi(+/-). Phys. Rev. D, 83(7), 071103–8pp.
Abstract: We report on a search for CP violation in the decay D-+/- -> K-S(0)pi(+/-) using a data set corresponding to an integrated luminosity of 469 fb(-1) collected with the BABAR detector at the PEP-II asymmetric energy e(+)e(-) storage rings. The CP- violating decay rate asymmetry A(CP) is determined to be (-0.44 +/- 0: 13(stat) +/- 0.10(syst))%, consistent with zero at 2.7 sigma and with the standard model prediction of (-0.332 +/- 0.006)%. This is currently the most precise measurement of this parameter.
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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(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Search for b -> u transitions in B- -> DK- and D*K- decays. Phys. Rev. D, 82(7), 072006–18pp.
Abstract: We report results from an updated study of the suppressed decays We report results from an updated study of the suppressed decays B- -> DK- and B- -> D*K- followed by D -> K+ pi(-), where D-(*()0) indicates a D-(*()0)or a (D) over bar (()*()0) meson, and D* -> D pi(0) or D* -> D gamma. These decays are sensitive to the Cabibbo-Kobayashi-Maskawa unitarity triangle angle gamma due to interference between the b -> c transition B- -> D-(*K-)0(-) followed by the doubly Cabibbo-suppressed decay D-0 -> K+ pi(-), and the b -> u transition B- -> (D) over bar (()*()0) K- followed by the Cabibbo-favored decay (D) over bar (0) -> K+ pi(-). We also report an analysis of the decay B- -> D-(*())pi(-) with the D decaying into the doubly Cabibbo-suppressed mode D -> K+ pi(-). Our results are based on 467 x 10(6) Gamma(4S) -> BB- decays collected with the BABAR detector at SLAC. We measure the ratios R-(*()) of the suppressed ([K+ pi(-)](D)K- / pi(-)) to favored ([K+ pi(-)](D)K- / pi(-)) branching fractions as well as the CP asymmetries A(()*()) of those modes. We see indications of signals for the B- -> DK- and B- -> D-D pi 0(()*()) K- suppressed modes, with statistical significances of 2.1 and 2.2 sigma, respectively, and we measure: R-DK = (1.1 +/- 0: 6 +/- 0.2) x 10(-2); A(DK) = -0.86 +/- 0: 47(-0.16)(+0.12), R-(D pi 0)K* = (1.8 +/- 0: 9 +/- 0: 4) x 10(-2); A ((D pi 0)K)* = +0.77 +/- 0: 35 +/- 0.12; R-(D gamma)K* = (1.3 +/- 1.4 +/- 0.8) x 10(-2); A((D gamma)K)* = +0.36 +/- 0: 94(-0.41)(+0.25), where the first uncertainty is statistical and the second is systematic. We use a frequentist approach to obtain the magnitude of the ratio r(B) equivalent to vertical bar A(B- -> (D) over bar 0K(-))/A(B- -> (DK-)-K-0)vertical bar = (9.5(-4.1)(+5.1))%, with r(B) < 16: 7% at 90% confidence level. In the case of B- -> D*K- we find r(B) equivalent to vertical bar A(B- -> <(D)over bar>0K(-))/A(B- -> (DK-)-K-0)vertical bar = (9.6(-5.1)(+3.5))%, with r(B)* < 15.0% at 90% confidence level.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Evidence for Direct CP Violation in the Measurement of the Cabbibo-Kobayashi-Maskawa Angle gamma with B-/+ -> D-(*K-)(()*()-/+) Decays. Phys. Rev. Lett., 105(12), 121801–7pp.
Abstract: We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating angle gamma through a Dalitz plot analysis of neutral D-meson decays to K-S(0)pi(+) pi(-) and K-S(0) K+ K- produced in the processes B--/+ -> DK -/+, B--/+ -> D* K--/+ with D* -> D pi(0), D gamma and B -/+ DK*-/+ with K*(-/+) -> K-S(0)pi(-/+), using 468 million B (B) over bar pairs collected by the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC. We measure gamma = (68 +/- 14 +/- 4 +/- 3)degrees (modulo 180 degrees), where the first error is statistical, the second is the experimental systematic uncertainty, and the third reflects the uncertainty in the description of the neutral D decay amplitudes. This result is inconsistent with gamma = 0 ( no direct CP violation) with a significance of 3.5 standard deviations.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2011). Observation of the Decay B- -> D_s(*) K- l- nu(bar). Phys. Rev. Lett., 107(4), 041804–8pp.
Abstract: We report the observation of the decay B(-) -> D(s)(()*()+)K(-)l(-)(nu) over bar (l) based on 342 fb(-1) of data collected at the Y(4S) resonance with the BABAR detector at the PEP-II e(+)e(-) storage rings at SLAC. A simultaneous fit to three D(s)(+) decay chains is performed to extract the signal yield from measurements of the squared missing mass in the B meson decay. We observe the decay B(-) -> D(s)(()*()+)K(-)l(-)(nu) over bar (l) with a significance greater than 5 standard deviations (including systematic uncertainties) and measure its branching fraction to be B(B(-) -> D(s)(()*())K(-)l(-)(nu) over bar (l) = [6.13(-1.03)(+1.04)(stat) +/- 0.43(syst) +/- 0.51 (B(D(s)))] X 10(-4), where the last error reflects the limited knowledge of the D(s) branching fractions.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2011). Search for the decay B-0 -> gamma gamma. Phys. Rev. D, 83(4), 032006–11pp.
Abstract: We report the result of a search for the rare decay B-0 -> gamma gamma in 426 fb(-1) of data, corresponding to 226 x 10(6) B-0(B) over bar (0) pairs, collected on the Y(4S) resonance at the PEP-II asymmetric-energy e(+)e(-) collider using the BABAR detector. We use a maximum likelihood fit to extract the signal yield and observe 21(-12)(+13) signal events with a statistical significance of 1.8 sigma. This corresponds to a branching fraction B(B-0 -> gamma gamma) = (1.7 +/- 1.1(stat.) +/- 0.2(syst.)) X 10(-7). Based on this result, we set a 90% confidence level upper limit of B(B-0 -> gamma gamma) < 3.2 X 10(-7).
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