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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Exclusive measurements of b -> s gamma transition rate and photon energy spectrum. Phys. Rev. D, 86(5), 052012–16pp.
Abstract: We use 429 fb(-1) of e(+)e(-) collision data collected at the Gamma(4S) resonance with the BABAR detector to measure the radiative transition rate of b -> s gamma with a sum of 38 exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be B((B) over bar -> X-s gamma) = (3.29 +/- 0.19 +/- 0.48) x 10(-4) where the first uncertainty is statistical and the second is systematic. We also measure the first and second moments of the photon energy spectrum and extract the best-fit values for the heavy-quark parameters, m(b) and mu(2)(pi), in the kinetic and shape function models.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2014). Bottomonium spectroscopy and radiative transitions involving the chi(bJ)(1P, 2P) states at BABAR. Phys. Rev. D, 90(11), 112010–20pp.
Abstract: We use (121 +/- 1) million Upsilon(3S) and (98 +/- 1) million Upsilon(2S) mesons recorded by the BABAR detector at the PEP-II e(+)e(-) collider at SLAC to perform a study of radiative transitions involving the chi(bJ)(1P, 2P) states in exclusive decays with mu(+)mu(-)gamma gamma final states. We reconstruct twelve channels in four cascades using two complementary methods. In the first we identify both signal photon candidates in the electromagnetic calorimeter (EMC), employ a calorimeter timing-based technique to reduce backgrounds, and determine branching-ratio products and fine mass splittings. These results include the best observational significance yet for the chi(b0)(2P) -> gamma Upsilon(2S) and chi(b0)(1P) -> gamma Upsilon(1S) transitions. In the second method, we identify one photon candidate in the EMC and one which has converted into an e(+)e(-) pair due to interaction with detector material, and we measure absolute product branching fractions. This method is particularly useful for measuring Upsilon(3S) -> gamma chi(b1,2)(1P) decays. Additionally, we provide the most up-to-date derived branching fractions, matrix elements and mass splittings for chi(b) transitions in the bottomonium system. Using a new technique, we also measure the two lowest-order spin-dependent coefficients in the nonrelativistic QCD Hamiltonian.
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Study of radiative bottomonium transitions using converted photons. Phys. Rev. D, 84(7), 072002–17pp.
Abstract: We use (111 +/- 1) million Gamma(3S) and (89 +/- 1) million Gamma(2S) events recorded by the BABAR detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to e(+)e(-) pairs by the detector material. We observe Gamma(3S) -> gamma chi b(0,2)(1P) decay, make precise measurements of the branching fractions for chi b(1,2)(1P, 2P) -> gamma Gamma(1S) and chi b(1,2)(2P) -> gamma Gamma(2S) decays, and search for radiative decay to the eta(b)(1S) and eta(b)(2S) states.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2011). Study of Y(3S, 2S) -> eta Y(1S) and Y(3S, 2S) -> pi(+) pi(-) Y(1S) hadronic transitions. Phys. Rev. D, 84(9), 092003–8pp.
Abstract: We study the Y(3S, 2S) -> eta Y(1S) and Y (3S,2S) -> pi(+)pi(-) transitions with 122 x 10(6) x Y(3S) and 100 x 10(6) Y (2S) mesons collected by the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider. We measure B[Y(2S) -> eta Y(1S)] = (2.39 +/- 0.31 (stat) +/- 0.14(syst)) x 10(-4) and Gamma[Y(2S) -> eta Y(1S)]/Gamma[Y(2S) ->pi(+)pi(-)(1S)] – (2.39 +/- 0.31(stat) +/- 0.14(syst)) x 10(-3). We find no evidence for Y(3S) -> eta Y (1S) and obtain B[Y(3S) -> eta Y(1S)] < 1.0 x 10(-4) and Gamma[Y (3S) -> eta Y(1S)/Gamma[Y(3S) -> pi(+)pi(-) Y(1S)] < 2.3 x 10(-3) as upper limits at the 90% confidence level. We also provide improved measurements of the Y(S) – Y(1S) and Y(3S) – Y (1S) mass differences, 562.170 +/- 0.007(stat) +/- 0.088(syst). MeV/c(2) and 893.813 +/- 0: 015(stat) +/- 0.107(syst.) MeV/c(2), respectively.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2018). Study of Upsilon(1S) radiative decays to gamma pi(+)pi(-) and gamma K+ K-. Phys. Rev. D, 97(11), 112006–17pp.
Abstract: We study the Upsilon(1S) radiative decays to gamma pi(+)pi(-) and gamma K+K- using data recorded with the BABAR detector operating at the SLAC PEP-11 asymmetric-energy e(+)e(-) collider at center-of-mass energies at the Upsilon(2S) and Upsilon(3S) resonances. The Upsilon(1S) resonance is reconstructed from the decay Upsilon(nS) -> pi(+)pi(-) Upsilon(1S), n =2, 3. Branching fraction measurements and spin-parity analyses of Upsilon(1S) radiative decays are reported for the I = 0 S-wave and f(2) (1270) resonances in the pi(+)pi(-) mass spectrum, the f'(2) (1525) and f(0) (1500) in the K+K mass spectrum, and the f(0)(1710) in both.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Measurement of the gamma gamma* -> eta and gamma gamma* -> eta ' transition form factors. Phys. Rev. D, 84(5), 052001–19pp.
Abstract: We study the reactions e(+)e(-) --> e(+)e(-) eta((')) in the single-tag mode and measure the gamma gamma* --> eta((')) transition form factors in the momentum-transfer range from 4 to 40 GeV(2). The analysis is based on 469 fb(-1) of integrated luminosity collected at PEP-II with the BABAR detector at e(+)e(-) center-of-mass energies near 10.6 GeV.
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BABAR Collaboration(Lees, J. P. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Measurement of the gamma gamma* -> eta c transition form factor. Phys. Rev. D, 81(5), 052010–18pp.
Abstract: We study the reaction e(+)e(-) -> e(+)e(-) eta(c), eta(c) -> KSK +/-pi(-/+) and obtain eta(c) mass and width values 2982.2 +/- 0.4 +/- 1.6 MeV/c(2) and 31.7 +/- 1.2 +/- 0.8 MeV, respectively. We find Gamma(eta(c) -> gamma gamma)B(eta(c) -> KK pi) = 0.374 +/- 0.009 +/- 0.031 keV, and measure the gamma gamma* -> eta(c) transition form factor in the momentum transfer range from 2 to 50 GeV2. The analysis is based on 469 fb(-1) of integrated luminosity collected at PEP-II with the BABAR detector at e(+)e(-) center-of-mass energies near 10.6 GeV.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2015). Study of B-+/-,B-0 -> J/psi(K+K-K +/-,0) and search for B-0 -> J/psi phi at BABAR. Phys. Rev. D, 91(1), 012003–12pp.
Abstract: We study the rare B meson decays B-+/-,B-0 -> J/psi(K+K-K +/-,0), B-+/-,B-0 -> J/psi phi K-+/-,K-0, and search for B-0 -> J/psi phi, using 469 x 10(6) B (B) over bar events collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II e(+)e(-) asymmetric energy collider. We present new measurements of branching fractions and a study of the J/psi phi mass distribution in search of new charmonium-like states. In addition, we search for the decay B-0 -> J/psi phi and find no evidence of a signal.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2014). Dalitz plot analysis of eta(c) -> K+K-eta and eta(c) -> K+K-pi(0) in two-photon interactions. Phys. Rev. D, 89(11), 112004–16pp.
Abstract: We study the processes gamma gamma -> K+K-eta and gamma gamma -> K+K-pi(0) using a data sample of 519 fb(-1) recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e(+)e(-) collider at center-of-mass energies at and near the Upsilon(nS) (n = 2, 3, 4) resonances. We observe eta(c) -> K+K-pi(0) and eta(c) -> K+K-eta decays, measure their relative branching fraction, and perform a Dalitz plot analysis for each decay. We observe the K*(0)(1430) -> K eta decay and measure its branching fraction relative to the K pi decay mode to be R(K*(0)(1430)) = B(K*(0)(1430)-> K eta)/B(K*(0)(1430)-> K pi) = 0.092 +/- 0.025(- 0.025)(+0.010). The eta(c) -> K+K-eta and K*(0)(1430) -> K eta results correspond to the first observations of these channels. The data also show evidence for eta(c)(2S) -> K+K-pi(0) and first evidence for eta(c)(2S) -> K+K-eta.
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2011). Observation of eta(c) (1S) and eta(c) (2S) decays to K(+)K(-) pi(+) pi(-) pi(0) in two-photon interactions. Phys. Rev. D, 84(1), 012004–9pp.
Abstract: We study the processes gamma gamma -> K(S)(0) K(-+) pi(-+) and gamma gamma -> K(+)K(-) pi(+)pi(-)pi(0) using a data sample of 519: 2fb(-1) recorded by the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at center-of-mass energies near the Y(nS) (n = 2, 3, 4) resonances. We observe the eta(c) (1S), chi(c0) (1P) and eta(c) (2S) resonances produced in two-photon interactions and decaying to K(+)K(-) pi(+)pi(-)pi(0), with significances of 18.1, 5.4 and 5.3 standard deviations (including systematic errors), respectively, and report 4.0 sigma evidence of the X(c2)(1P) decay to this final state. We measure the eta(c)(2S) mass and width in K(S)(0) K(+-) pi(+-) decays, and obtain the values m(eta(c)(2S)) = 3638: 5 +/- 1.5 +/- 0.8 MeV/c(2) and Gamma(eta(c)(2S)) = 13.4 +/- 4: 6 +/- 3.2 MeV, where the first uncertainty is statistical and the second is systematic. We measure the two-photon width times branching fraction for the reported resonance signals, and search for the X(c2) (2P) resonance, but no significant signal is observed.
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