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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). 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). Searches for rare or forbidden semileptonic charm decays. Phys. Rev. D, 84(7), 072006–13pp.
Abstract: We present searches for rare or forbidden charm decays of the form X(c)(+) -> h(+/-)l(+/-)l((l)+), where X(c)(+) is a charm hadron (D(+), D(s)(+), or A(c)(+)), h +/- is a pion, kaon, or proton, and l((l)+/-) is an electron or muon. The analysis is based on 384 fb(-1) of e(+)e(-) annihilation data collected at or close to the gamma(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the 35 decay modes that are investigated. We establish 90% confidence-level upper limits on the branching fractions between 1 x 10(-6) and 44 x 10(-6) depending on the channel. In most cases, these results represent either the first limits or significant improvements on existing limits for the decay modes studied.
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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), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Evidence for the h(b)(1P) meson in the decay Y(3S) -> pi(0)h(b)(1P). Phys. Rev. D, 84(9), 091101–8pp.
Abstract: Using a sample of 122 x 10(6) Y(3S) events recorded with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC, we search for the h(b)(1P) spin-singlet partner of the P-wave X(bJ)(1P) states in the sequential decay Y(3S) -> pi(0)h(b) (1P), hb(1P) -> gamma eta(b)(1S). We observe an excess of events above background in the distribution of the recoil mass against the pi(0) at mass 9902 +/- 4(stat) +/- 2(syst) MeV/c(2). The width of the observed signal is consistent with experimental resolution, and its significance is 3.1 sigma, including systematic uncertainties. We obtain the value (4.3 +/- 1.1(stat) +/- 0.9(syst) x 10(-4) for the product branching fraction B(Y(3S) -> pi(0)h(b)) XB (h(b) -> gamma eta(b))
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2022). Search for Darkonium in e(+) e(-) Collisions. Phys. Rev. Lett., 128(2), 021802–7pp.
Abstract: Collider searches for dark sectors, new particles interacting only feebly with ordinary matter, have largely focused on identifying signatures of new mediators, leaving much of dark sector structures unexplored. In particular, the existence of dark matter bound states (darkonia) remains to be investigated. This possibility could arise in a simple model in which a dark photon (A') is light enough to generate an attractive force between dark fermions. We report herein a search for a J(PC) = 1(--) darkonium state, the Upsilon(D), produced in the reaction e(+) e(-) -> gamma Upsilon(D), Upsilon(D) -> A'A'A', where the dark photons subsequently decay into pairs of leptons or pions, using 514 fb(-1) of data collected with the BABAR detector. No significant signal is observed, and we set bounds on the gamma – A' kinetic mixing as a function of the dark sector coupling constant for 0.001 < m(A)' < 3.16 GeV and 0.05 < m(Upsilon D) < 9.5 GeV.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2022). Search for Lepton Flavor Violation in Upsilon(3S) -> e(+/-)mu(-/+). Phys. Rev. Lett., 128(9), 091804–7pp.
Abstract: We report on the first search for electron-muon lepton flavor violation (LFV) in the decay of a b quark and b antiquark bound state. We look for the LFV decay Upsilon(3S) -> e(+/-) mu(-/+) in a sample of 118 million gamma(3S) mesons from 27 fb(-1) of data collected with the BABAR detector at the SLAC PEP-II e(+) e(-) collider operating with a 10.36 GeV center-of-mass energy. No evidence for a signal is found, and we set a limit on the branching fraction B[Upsilon(3S) -> e(+/-) mu(-/+)] < 3.6 x 10(-7) at 90% C. L. This result can be interpreted as a limit Lambda(NP)/g(NP)(2) > 80 TeV on the energy scale Lambda(NT) divided by the coupling-squared g(NP)(2) of relevant new physics (NP).
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2022). Search for an Axionlike Particle in B Meson Decays. Phys. Rev. Lett., 128(13), 131802–8pp.
Abstract: Axionlike particles (ALPs) are predicted in many extensions of the standard model, and their masses can naturally be well below the electroweak scale. In the presence of couplings to electroweak bosons, these particles could be emitted in flavor-changing B meson decays. We report herein a search for an ALP, a, in the reaction B-+/- -> K(+/-)a, a -> gamma gamma using data collected by the BABAR experiment at SLAC. No significant signal is observed, and 90% confidence level upper limits on the ALP coupling to electroweak bosons are derived as a function of ALP mass, improving current constraints by several orders of magnitude in the range 0.175 GeV < m(a) < 4.78 GeV.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2021). Study of the reactions e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)pi(0) and 2(pi(+)pi(-))pi(0)pi(0)eta at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation. Phys. Rev. D, 103(9), 092001–21pp.
Abstract: We study the processes e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)pi(0)gamma and 2(pi(+)pi(-))pi(0)pi(0)eta gamma in which an energetic photon is radiated from the initial state. The data were 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. The center-of-mass energies range from threshold to 4.5 GeV. From the mass spectra, the first ever measurements of the e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)pi(0) and the e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)eta cross sections are performed. The contributions from omega pi(+)pi(-)pi(0)pi(0), eta 2(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. (2021). Light meson spectroscopy from Dalitz plot analyses of eta(c) decays to eta ' K+K-, eta 'pi(+)pi(-), and eta pi(+)pi(-) produced in two-photon interactions. Phys. Rev. D, 104(7), 072002–23pp.
Abstract: We study the processes gamma gamma -> eta(c )-> eta'K+K-, eta'pi(+)pi(-), and eta pi(+)pi(-) 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. This is the first observation of the decay eta(c)-> eta'K+K- and we measure the branching fraction Gamma (eta(c) -> eta' K+K- )/(Gamma(eta(c) -> eta'pi(+)pi(-)) = 0.644 +/- 0.039(stat) +/- 0.032(sys). Significant interference is observed between gamma gamma ->eta(c)->eta pi(+)pi(-) and the nonresonant two-photon process gamma gamma -> eta pi(+)pi(-). A Dalitz plot analysis is performed of eta(c) decays to eta'K+K-, eta'pi(+)pi(-) and eta pi(+)pi(-). Combined with our previous analysis of eta(c) -> K (K) over bar pi, we measure the K-0*(1430) parameters and the ratio between its eta'K and pi K couplings. The decay eta(c) -> eta'pi(+)pi(-) is dominated by the f(0)(2100) resonance, also observed in J/psi radiative decays. A new a(0) (1700) -> eta pi resonance is observed in the eta(c) -> eta pi(+)pi(-) channel. We also compare eta(c) decays to eta and eta' final states in association with scalar mesons as they relate to the identification of the scalar glueball.
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