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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. (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). Measurement of the absolute branching fractions for D-s(-) -> l(-) (nu)over-bar(l) and extraction of the decay constant f(Ds). Phys. Rev. D, 82(9), 091103–8pp.
Abstract: The absolute branching fractions for the decays D-s(-) -> l(-) (nu) over bar (l) (l = e, mu, or tau) are measured using a data sample corresponding to an integrated luminosity of 521 fb(-1) collected at center-of-mass energies near 10.58 GeV with the BABAR detector at the PEP-II e(+)e(-) collider at SLAC. The number of D-s(-) mesons is determined by reconstructing the recoiling system DKX gamma in events of the type e(+)e(-) -> DKXDs*(-), where D-s*(-) -> D-s(-) gamma and X represents additional pions from fragmentation. The D-s(-) -> l(-) nu(l) events are detected by full or partial reconstruction of the recoiling system DKX gamma l. The branching fraction measurements are combined to determine the D-s(-) decay constant f(Ds) (258.6 +/- 6.4 +/- 7:5) MeV, where the first uncertainty is statistical and the second is systematic.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Exclusive production of Ds+Ds-,D-s*D-+(s)-, and D-s*D-+(s)*(-) via e(+)e(-) annihilation with initial-state radiation. Phys. Rev. D, 82(5), 052004–10pp.
Abstract: We perform a study of exclusive production of Ds+Ds-,D-s*(+),D-s(-), and D-s*D-+(s)*- final states in initial-state radiation events from e(+)e(-) annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium 1(--) states. The data sample corresponds to an integrated luminosity of 525 fb(-1) and was recorded by the BABAR experiment at the PEP-II storage ring. Ds+Ds-,D-s*(+),D-s(-) and ,D-s*(+),D-s*(-) mass spectra show evidence of the known psi resonances. Limits are extracted for the branching ratios of the decays X(4260) -> D-s(()*()+) D-s(()*()-)
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