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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Search for resonances decaying to eta(c)pi(+) pi(-) in two-photon interactions. Phys. Rev. D, 86(9), 092005–10pp.
Abstract: We report a study of the process gamma gamma -> X -> eta(c)pi(+)pi(-) , where X stands for one of the resonances chi(c2)(1P), eta(c)(2S), X(3872), X(3915), or chi(c2)(2P). The analysis is performed with a data sample of 473.9 fb(-1) collected with the BABAR detector at the PEP-II asymmetric-energy electron-positron collider. We do not observe a significant signal for any channel, and calculate 90% confidence-level upper limits on the products of branching fractions and two-photon widths Gamma B-x ->gamma gamma(X -> eta(c)pi(+) pi(-)): 15.7 eV for chi(c2)(1P), 133 eV for eta(c)(2S), 11.1 eV for X(3872) (assuming it to be a spin-2 state), 16 eV for X(3915) (assuming it to be a spin-2 state), and 18 eV for chi(c2)(2P). We also report upprt limits on the rations of branching fractions B(eta(c)(2S) -> eta(c)pi(+) pi(-))/B(eta(c)(2S) -> (KSK+)-K-0 pi(-)) < 10.0 and B(chi(c2)(1P) -> eta(c)pi(+) pi(-))/B(chi(c2)(1P) -> (KSK+)-K-0 pi(-)) < 32.9 at the 90% confidence level.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2011). Observation of the rare decay B(+) -> K(+) pi(0)pi(0) and measurement of the quasi-two-body contributions B(+) -> K* (892)(+) pi(0), B(+) -> f(0)(980)K(+), and B(+) -> chi(c0)K(+). Phys. Rev. D, 84(9), 092007–11pp.
Abstract: We report an analysis of charmless hadronic decays of charged B mesons to the final state K(+) pi(0)pi(0), using a data sample of (470.9 +/- 2.8) x 10(6) B (B) over bar events collected with the BABAR detector at the Y(4S) resonance. We observe an excess of signal events, with a significance above 10 standard deviations including systematic uncertainties, and measure the branching fraction and CP asymmetry to be B(B(+) -> K(+) pi(0)pi(0)) = (16.2 +/- 1.2 +/- 1.5) x 10(-6) and A(CP)(B(+) -> K(+) pi(0)pi(0)) = -0.06 +/- 0.06 +/- 0.04, where the uncertainties are statistical and systematic, respectively. Additionally, we study the contributions of the B(+) -> K*(892)(+) pi(0), B(+) -> f(0)(980)K(+), and B(+) -> chi(c0)K(+) quasi-two-body decays. We report the world's best measurements of the branching fraction and CP asymmetry of the B(+) -> K(+) pi(0)pi(0) and B(+) -> K(+)(892)(+) pi(0) channels.
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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. (2020). Precision Measurement of the Ratio B(gamma(3S) -> tau(+)tau(-))/B(gamma(3S) -> mu(+)mu(-)). Phys. Rev. Lett., 125(24), 241801–7pp.
Abstract: We report on a precision measurement of the ratio R-tau mu(gamma(3s)) = B(gamma(3S) -> tau(+)tau(-))/B(tau(gamma(3S) ->mu(+)mu(-)) using data collected with the BABAR detector at the SLAC PEP-II e(+)e(-) collider. The measurement is based on a 28 fb(-1) data sample collected at a center-of-mass energy of 10.355 GeV corresponding to a sample of 122 million gamma(35) mesons. The ratio is measured to be R-tau mu(gamma(3s)) = 0.966 +/- 0.008(stat) +/- 0.014(syst) and is in agreement with the standard model prediction of 0.9948 within 2 standard deviations. The uncertainty in R-tau mu(gamma(3s)) is almost an order of magnitude smaller than the only previous measurement.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2013). Search for direct CP violation in singly Cabibbo-suppressed D-+/- -> K+K-pi(+/-) decays. Phys. Rev. D, 87(5), 052010–12pp.
Abstract: We report on a search for direct CP violation in the singly Cabibbo-suppressed decay D+ -> K+K-pi(+/-) using a data sample of 476 fb(-1) of e(+)e(-) annihilation data accumulated with the BABAR detector at the SLAC PEP-II electron-positron collider, running at and just below the energy of the Upsilon(4S) resonance. The integrated CP-violating decay rate asymmetry A(CP) is determined to be (0.37 +/- 0.30 +/- 0.15)%. Model-independent and model-dependent Dalitz plot analysis techniques are used to search for CP-violating asymmetries in the various intermediate states. We find no evidence for CP-violation asymmetry.
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