BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2015). Measurement of the branching fractions of the radiative leptonic tau decays tau -> e gamma v(v)over-bar and tau -> μgamma v(v)over-bar at BABAR. Phys. Rev. D, 91(5), 051103–8pp.
Abstract: We perform a measurement of the tau -> l gamma v (v) over bar (l = e, mu) branching fractions for a minimum photon energy of 10 MeV in the tau rest frame, using 431 fb(-1) of e(+) e(-) collisions collected at the center-of-mass energy of the Upsilon(4S) resonance with the BABAR detector at the PEP-II storage rings. We find B(tau -> μgamma v (v) over bar = (3.69 +/- 0.03 +/- 0.10) x 10(-3) and B(tau -> e gamma v (v) over bar = (1.847 +/- 0.015 +/- 0.052) x 10(-2), where the first quoted error is statistical and the second is systematic. These results are substantially more precise than previous measurements.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2015). Search for a light Higgs resonance in radiative decays of the Upsilon(1S) with a charm tag. Phys. Rev. D, 91(7), 071102–9pp.
Abstract: A search is presented for the decay Upsilon(1S) -> gamma A(0), A(0) -> c (c) over barc, where A(0) is a candidate for the CP-odd Higgs boson of the next-to-minimal supersymmetric standard model. The search is based on data collected with the BABAR detector at the Upsilon(2S) resonance. A sample of Upsilon(1S) mesons is selected via the decay Upsilon(2S) -> pi(+)pi(-)Upsilon(1S) . The A(0) -> c (c) over bar decay is identified through the reconstruction of hadronic D-0, D+,and D-0 (2010)(+) meson decays. No significant signal is observed. The measured 90% confidence-level upper limits on the product branching fraction beta(Upsilon(1S) -> gamma A(0)) x beta(A(0) -> (c) over barc range from 7.4 x 10(-5) to 2.4 x 10(-3) for A(0) masses from 4.00 to 8.95 GeV/c(2) and 9.10 to 9.25 GeV/c(2), where the region between 8.95 and 9.10 GeV/c(2) is excluded because of background from Upsilon(2S) -> gamma chi(bJ)(1P), chi(bJ)(1P) -> gamma Upsilon(1S) decays.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). First observation and amplitude analysis of the B- -> D+K-pi(-) decay. Phys. Rev. D, 91(9), 092002–24pp.
Abstract: The B- -> D+K-pi(-) decay is observed in a data sample corresponding to 3.0 fb(-1) of pp collision data recorded by the LHCb experiment during 2011 and 2012. Its branching fraction is measured to be B(B- -> D+K-pi(-)) = (7.31 +/- 0.19 +/- 0.22 +/- 0.39) x 10(-5) where the uncertainties are statistical, systematic and from the branching fraction of the normalization channel B- -> D+pi(-)pi(-), respectively. An amplitude analysis of the resonant structure of the B- -> D+K-pi(-) decay is used to measure the contributions from quasi-two-body B- -> D-0* (2400)K-0(-), B- -> D-2* (2460)K-0(-), and B- -> D-J* (2760)K-0(-) decays, as well as from nonresonant sources. The D-J* (2760)(0) resonance is determined to have spin 1.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Study of CP violation in B-/+ -> Dh(-/+) (h = K,pi) with the modes D -> K-/+pi(+/-)pi(0), D -> pi(+)pi(-)pi(0) and D -> K+K-pi(0). Phys. Rev. D, 91(11), 112014–15pp.
Abstract: An analysis of the decays of B--/+ -> DK -/+ and B--/+ -> D pi(-/+) is presented in which the D meson is reconstructed in the three-body final states K--/+pi(+/-)pi(0), pi(+)pi(-)pi(0) and K+K-pi(0). Using data from LHCb corresponding to an integrated luminosity of 3.0 fb(-1) of pp collisions, measurements of several CP observables are performed. First observations are obtained of the suppressed Atwood-Dunietz-Soni decay B--/+ -> [pi K-+(+/-)pi(0)](D)pi(-/+) and the quasi-Gronau-London-Wyler decay B--/+ -> [K+K-pi(0)](D)pi(-/+). The results are interpreted in the context of the unitarity triangle angle gamma and related parameters.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Amplitude analysis of B-0 -> (D)over-bar0K(+)pi(-) decays. Phys. Rev. D, 92(1), 012012–24pp.
Abstract: The Dalitz plot distribution of B-0 -> (D) over bar K-0(+)pi(-) decays is studied using a data sample corresponding to 3.0 fb(-1) of pp collision data recorded by the LHCb experiment during 2011 and 2012. The data are described by an amplitude model that contains contributions from intermediate K* (892)(0), K*(1410)(0), K-2*(1430)(0) and D-2(*)(2460)(-) resonances. The model also contains components to describe broad structures, including the K-0(*)(1430)(0) and D-0(*)(2400)(-) resonances, in the K pi S-wave and the D pi S-and P-waves. The masses and widths of the D-0*(2400)(-) and D-2(*)(2460)(-) resonances are measured, as are the complex amplitudes and fit fractions for all components included in the amplitude model. The model obtained will be an integral part of a future determination of the angle gamma of the Cabibbo-Kobayashi-Maskawa quark mixing matrix using B-0 -> DK+pi(-) decays.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Dalitz plot analysis of B-0 -> (D)over-bar(0)pi(+)pi(-) decays. Phys. Rev. D, 92(3), 032002–40pp.
Abstract: The resonant substructures of B-0 --> (D) over bar (0)pi(+)pi(-) decays are studied with the Dalitz plot technique. In this study a data sample corresponding to an integrated luminosity of 3.0 fb(-1) of pp collisions collected by the LHCb detector is used. The branching fraction of the B-0 --> (D) over bar (0)pi(+)pi(-) decay in the region m((D) over bar (0)pi(+/-)) > 2.1 GeV/c(2) is measured to be (8.46 +/- 0.14 +/- 0.29 +/- 0.40) x 10(-4), where the first uncertainty is statistical, the second is systematic and the last arises from the normalization channel B-0 --> D*(2010)(-)pi(+). The pi(+)pi(-) S-wave components are modeled with the isobar and K-matrix formalisms. Results of the Dalitz plot analyses using both models are presented. A resonant structure at m((D) over bar (0)pi(-)) approximate to 2.8 GeV/c(2) is confirmed and its spin-parity is determined for the first time as J(P) = 3(-). The branching fraction, mass and width of this structure are determined together with those of the D-0*(2400)(-) and D-2*(2460)(-) resonances. The branching fractions of other B-0 --> (D) over bar (0)h(0) decay components with h(0) --> pi(+)pi(-) also reported. Many of these branching fraction measurements are the most precise to date. The first observation of the decays B0 --> (D) over bar (0)f(0)(500), B-0 --> (D) over bar (0)f(0)(980), B-0 --> (D) over bar (0)rho(1450), B-0 --> D-3(*)(2760)(-)pi(+) and the first evidence of B-0 --> (D) over bar (0)f(0)(2020) are presented.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Quantum numbers of the X(3872) state and orbital angular momentum in its rho(0)J/psi decay. Phys. Rev. D, 92(1), 011102–9pp.
Abstract: Angular correlations in B+ -> X(3872)K+ decays, with X(3872) -> rho(0)J/psi, rho(0) -> pi(+)pi(-) and J/psi -> pi(+)pi(-), are used to measure orbital angular momentum contributions and to determine the J(PC) value of the X(3872) meson. The data correspond to an integrated luminosity of 3.0 fb(-1) of proton- proton collisions collected with the LHCb detector. This determination, for the first time performed without assuming a value for the orbital angular momentum, confirms the quantum numbers to be J(PC) = 1(++). The X(3872) is found to decay predominantly through an S wave and an upper limit of 4% at 95% C.L. is set on the D-wave contribution.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Study of W boson production in association with beauty and charm. Phys. Rev. D, 92(5), 052001–16pp.
Abstract: The associated production of a W boson with a jet originating from either a light parton or heavy-flavor quark is studied in the forward region using proton-proton collisions. The analysis uses data corresponding to integrated luminosities of 1.0 and 2.0 fb(-1) collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, respectively. The W bosons are reconstructed using the W -> μnu decay and muons with a transverse momentum, p(T), larger than 20 GeV in the pseudorapidity range 2.0 < eta < 4.5. The partons are reconstructed as jets with p(T) > 20 GeV and 2.2 < eta < 4.2. The sum of the muon and jet momenta must satisfy p(T) > 20 GeV. The fraction of W + jet events that originate from beauty and charm quarks is measured, along with the charge asymmetries of the W+b and W+c production cross sections. The ratio of the W + jet to Z + jet production cross sections is also measured using the Z -> μμdecay. All results are in agreement with Standard Model predictions.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Measurement of the branching fraction ratio B(B-c(+) -> psi(2S)pi(+))/B(B-c(+) -> J/psi pi(+)). Phys. Rev. D, 92(7), 072007–10pp.
Abstract: Using pp collision data collected by LHCb at center-of-mass energies root s = 7 TeV and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1), the ratio of the branching fraction of the B-c(+) -> psi(2S)pi(+) decay relative to that of the B-c(+) -> J/psi pi(+) decay is measured to be 0.268 +/- 0.032(stat) +/- 0.007(syst) +/- 0.006(BF). The first uncertainty is statistical, the second is systematic, and the third is due to the uncertainties on the branching fractions of the J/psi -> mu(+)mu(-) and psi(2S) -> mu(+)mu(-) decays. This measurement is consistent with the previous LHCb result, and the statistical uncertainty is halved.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2015). Study of the e(+)e(-) -> K+K- reaction in the energy range from 2.6 to 8.0 GeV. Phys. Rev. D, 92(7), 072008–16pp.
Abstract: The e(+)e(-) -> K+K- cross section and charged-kaon electromagnetic form factor are measured in the e(+)e(-) center-of-mass energy range (E) from 2.6 to 8.0 GeV using the initial-state radiation technique with an undetected photon. The study is performed using 469 fb(-1) of data collected with the BABAR detector at the PEP-II2 e(+)e(-) collider at center-of-mass energies near 10.6 GeV. The form factor is found to decrease with energy faster than 1/E-2 and approaches the asymptotic QCD prediction. Production of the K+K- final state through the J/psi and psi(2S) intermediate states is observed. The results for the kaon form factor are used together with data from other experiments to perform a model-independent determination of the relative phases between electromagnetic (single-photon) and strong amplitudes in J/psi and psi(2S). K+K- decays. The values of the branching fractions measured in the reaction e(+)e(-) -> K+K- are shifted relative to their true values due to interference between resonant and nonresonant amplitudes. The values of these shifts are determined to be about +/- 5% for the J/psi meson and +/- 15% for the psi(2S) meson.
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