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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 the rare decay B -> Kv(v)over-bar. Phys. Rev. D, 82(11), 112002–10pp.
Abstract: We present a search for the rare decays B+ -> K+ v (v) over bar and B-0 -> K-0 v (v) over bar using 459 x 10(6) B (B) over bar pairs collected with the BABAR detector at the SLAC National Accelerator Laboratory. Flavor-changing neutral-current decays such as these are forbidden at tree level but can occur through one-loop diagrams in the standard model (SM), with possible contributions from new physics at the same order. The presence of two neutrinos in the final state makes identification of signal events challenging, so reconstruction in the semileptonic decay channels B -> D-(*) lv of the B meson recoiling from the signal B is used to suppress backgrounds. We set an upper limit at the 90% confidence level (CL) of 1.3 x 10(-5) on the total branching fraction for B+ -> K+ v (v) over bar, and 5.6 x 10(-5) for B-0 -> K-0 v (v) over bar. We additionally report 90% CL upper limits on partial branching fractions in two ranges of dineutrino mass squared for B+ -> K+ v (v) over bar.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Observation of new resonances decaying to D pi and D*pi in inclusive e(+)e(-) collisions near root s=10.58 GeV. Phys. Rev. D, 82(11), 111101–9pp.
Abstract: We present a study of the D+pi(-), D-0 pi(+), and D*(+)pi(-) systems in inclusive e(+)e(-)-> c (c) over bar interactions in a search for new excited D meson states. We use a data set, consisting of similar to 454 fb(-1), collected at center-of-mass energies near 10.58 GeV by the BABAR detector at the SLAC PEP-II asymmetric-energy collider. We observe, for the first time, candidates for the radial excitations of the D-0, D*(0), and D*(+), as well as the L = 2 excited states of the D-0 and D+, where L is the orbital angular momentum of the quarks.
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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), 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(Aubert, B. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Correlated leading baryon-antibaryon production in e(+)e(-) -> c(c)over-bar -> Lambda(+)(c)(Lambda)over-bar(c)(-)X. Phys. Rev. D, 82(9), 091102–8pp.
Abstract: We present a study of 649 +/- 35 e(+)e(-) -> c (c) over bar events produced at root s approximate to 10.6 GeV containing both Lambda(+)(c) baryon and a (Lambda) over bar (-)(c) antibaryon. The number observed is roughly 4 times that expected if the leading charmed hadron types are uncorrelated, confirming an observation by the CLEO Collaboration. We find a 2-jet topology in these events but very few additional baryons, demonstrating that the primary c and (c) over bar are predominantly contained in a correlated baryon-antibaryon system. In addition to the charmed baryons we observe on average 2.6 +/- 0.2 charged intermediate mesons, predominantly pions, carrying 65% of the remaining energy.
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