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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Amplitude analysis and measurement of the time-dependent CP asymmetry of B-0 -> (KSKSKS0)-K-0-K-0 decays. Phys. Rev. D, 85(5), 054023–21pp.
Abstract: We present the first results on the Dalitz-plot structure and improved measurements of the time-dependent CP-violation parameters of the process B-0 -> (KSKSKS0)-K-0-K-0 obtained using 468 x 10(6) B (B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The Dalitz-plot structure is probed by a time-integrated amplitude analysis that does not distinguish between B-0 and (B) over bar (0) decays. We measure the total inclusive branching fraction B(B-0 -> (KSKSKS0)-K-0-K-0) = (6.19 +/- 0.48 +/- 0.15 +/- 0.12) x 10(-6), where the first uncertainty is statistical, the second is systematic, and the third represents the Dalitz-plot signal model dependence. We also observe evidence for the intermediate resonant states f(0)(980), f(0)(1710), and f(2)(2010). Their respective product branching fractions are measured to be (2.70(-1.19)(+1.25) +/- 0.36 +/- 1.17) x 10(-6), (0.50(-0.24)(+0.46) +/- 0.04 +/- 0.10) x 10(-6), and (0.54(-0.20)(+0.21) +/- 0.03 +/- 0.52) x 10(-6). Additionally, we determine the mixing-induced CP-violation parameters to be S = -0.94(-0.21)(+0.24) +/- 0.06 and C = -0.17 +/- 0.18 +/- 0.04, where the first uncertainty is statistical and the second is systematic. These values are in agreement with the standard model expectation. For the first time, we report evidence of CP violation in B-0 -> (KSKSKS0)-K-0-K-0 decays; CP conservation is excluded at 3.8 standard deviations including systematic uncertainties.
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2012). Search for the decay D-0 -> gamma gamma and measurement of the branching fraction for D-0 -> pi(0)pi(0). Phys. Rev. D, 85(9), 091107–8pp.
Abstract: We search for the rare decay of the D-0 meson to two photons, D-0 -> gamma gamma, and present a measurement of the branching fraction for a D-0 meson decaying to two neutral pions, B(D-0 -> pi(0)pi(0)). The data sample analyzed corresponds to an integrated luminosity of 470.5 fb(-1) collected by the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC. We place an upper limit on the branching fraction, B(D-0 -> gamma gamma) < 2.2 x 10(-6), at 90% confidence level. This limit improves on the existing limit by an order of magnitude. We also find B(D-0 -> pi(0)pi(0)) = (8.4 +/- 0.1 +/- 0.4 +/- 0.3 +/-) x 10(-4).
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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), 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), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Measurements of branching fractions and CP asymmetries and studies of angular distributions for B -> phi phi K decays. Phys. Rev. D, 84(1), 012001–13pp.
Abstract: We present branching fraction and CP asymmetry measurements as well as angular studies of B -> phi phi K decays using 464 x 10(6) B (B) over bar events collected by the BABAR experiment. The branching fractions are measured in the phi phi invariant mass range below the eta(c) resonance (m(phi phi) < 2.85 GeV). We find B(B(+) -> phi phi K(+)) = (5.6 +/- 0.5 +/- 0.3) x 10(-6) and B(B(0) -> phi phi K(0)) = (4.5 +/- 0.8 +/- 0.3) x 10(-6), where the first uncertainty is statistical and the second systematic. The measured direct CP asymmetries for the B(+/-) decays are A(CP) = -0.10 +/- 0.08 +/- 0: 02 below the eta(c) threshold (m(phi phi) < 2.85 GeV) and A(CP) = 0.09 +/- 0.10 +/- 0.02 in the eta(c) resonance region (m(phi phi) in [2.94, 3.02] GeV). Angular distributions are consistent with J(P) = 0(-) in the eta(c) resonance region and favor J(P) = 0(+) below the eta(c) resonance.
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Search for b -> u transitions in B(+/-) -> [K(-/+)pi(+/-)pi(0)](D)K(+/-) decays. Phys. Rev. D, 84(1), 012002–10pp.
Abstract: We present a study of the decays B(+) -> DK(+) with D mesons reconstructed in the K(+)pi(-)pi(0) or K(-)pi(+)pi(0) final states, where D indicates a D(0) or a (D) over bar (0) meson. Using a sample of 474 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP- II asymmetric- energy e(+)e(-) collider at SLAC, we measure the ratios R +/- equivalent to Gamma(B(+)->[K(-/+)pi(+)pi(0)](D)K(+))/Gamma(B(+)->[K(+)pi(-/+)pi(0)](D) K(+)). We obtain R+ = (5(-10)(+12)(stat)(4)(2)(syst)) X 10(-3) and R(-) = (12(-10)(+12)(stat)(-5)(+3)(syst)) X 10(-3), from which we extract the upper limits at 90% probability: R(+) < 23 X 10(-3) and R- < 29 X 10(-3). Using these measurements, we obtain an upper limit for the ratio r(B) of the magnitudes of the b -> u and b -> c amplitudes r(B) < 0.13 at 90% probability.
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Measurement of the mass and width of the D_s1 (2536)+ meson. Phys. Rev. D, 83(7), 072003–14pp.
Abstract: The decay width and mass of the D-s1(2536)(+) meson are measured via the decay channel D-s1(+) -> (D*+KS0) using 385 fb(-1) of data recorded with the BABAR detector in the vicinity of the Gamma(4S) resonance at the PEP-II asymmetric-energy electron-positron collider. The result for the decay width is Gamma(D-s1(+)) = 92 +/- 0.03(stat.) +/- 0.04(syst.) MeV. For the mass, a value of m(D-s1(+)) = 2535.08 +/- 0.01(stat.) +/- 0.15(syst.) MeV/c(2) is obtained. The mass difference between the D-s1(+) and the D*+ is measured to be m(D-s1(+)) – m(D*+) = 524.83 +/- 0.01(stat.) +/- 0.04(syst.) MeV/c(2), representing a significant improvement compared to the current world average. The unnatural spin-parity assignment for the D-s1(+) meson is confirmed.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2018). Study of the reactions e(+)e(-) -> pi(+)pi(-)pi(0)pi(0)pi(0) and pi(+)pi(-) pi(0)pi(0)eta at center-of-mass energies from threshold to 4.35 GeV using initial-state radiation. Phys. Rev. D, 98(11), 112015–23pp.
Abstract: We study the processes e(+)e--> pi(+)pi(-)pi(0)pi(0)pi(0)gamma and pi(+)pi(-)pi(0)pi(0)eta gamma in which an energetic photon is radiated from the initial state. The data are collected with the BABAR detector at SLAC. About 14 000 and 4700 events, respectively, are selected from a data sample corresponding to an integrated luminosity of 469 fb(-1). The invariant mass of the hadronic final state defines the effective e(+)e(-) center-of-mass energy. From the mass spectra, the first precise measurement of the e(+)e--> pi(+)pi(-)pi(0)pi(0)pi(0) cross section and the first measurement ever of the e(+)e--> pi(+)pi(-)pi(0)pi(0)pi(0)eta cross section are performed. The center-of-mass energies range from threshold to 4.35 GeV. The systematic uncertainty is typically between 10% and 13%. The contributions from omega pi(0)pi(0), eta pi(+)pi(-) and other intermediate states are presented. We observe the J/psi and psi(2S) in most of these final states and measure the corresponding branching fractions, many of them for the first time.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2018). Measurement of the gamma*gamma* -> eta ' transition form factor. Phys. Rev. D, 98(11), 112002–11pp.
Abstract: We study the process e(+)e(-) -> e(+)e(-)eta' in the double-tag mode and measure for the first time the gamma*gamma* -> eta' transition form factor F-eta'(Q(1)(2), Q(2)(2)) in the momentum-transfer range 2 < Q(1)(2), Q(2)(2) < 60 GeV2. The analysis is based on a data sample corresponding to an integrated luminosity of around 469 fb(-1) collected at the PEP-II e(+)e(-) collider with the BABAR detector at center-of-mass energies near 10.6 GeV.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2018). Measurement of the spectral function for the tau(-) -> K- K(S)v(tau) decay. Phys. Rev. D, 98(3), 032010–11pp.
Abstract: The decay tau(-) -> K- K(S)v(tau) has been studied using 430 x 10(6) e(+) e(-) -> tau(+) tau(-) events produced at a center-of-mass energy around 10.6 GeV at the PEP-II collider and studied with the BABAR detector. The mass spectrum of the K- K-S system has been measured and the spectral function has been obtained. The measured branching fraction B(tau(-) -> K- K(S)v(tau)) = (0.739 +/- 0.011 (stat) +/- 0.020 (syst)) x 10(-3) is found to be in agreement with earlier measurements.
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