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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2013). Evidence of B+ -> tau(+)nu decays with hadronic B tags. Phys. Rev. D, 88(3), 031102–9pp.
Abstract: We present a search for the decay B+ -> tau(+)nu using 467.8 x 10(6) B (B) over bar pairs collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. We select a sample of events with one completely reconstructed B- in the hadronic decay mode (B- -> D-(*X-)0(-) and B- -> J/psi X-). We examine the rest of the event to search for a B+ -> tau(+)nu decay. We identify the tau(+) lepton in the following modes: tau(+) -> e(+)nu(nu) over bar, tau(+) -> mu(+)nu(nu) over bar, tau(+) -> pi(+)(nu) over bar and tau(+) -> rho(+)(nu) over bar. We find an excess of events with respect to the expected background, which excludes the null signal hypothesis at the level of 3.8 sigma (including systematic uncertainties) and corresponds to a branching fraction value of B(B+ -> tau(+)nu) = (1.83(-0.49)(+0.53)(stat) +/- 0.24(syst)) x 10(-4).
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BABAR Collaboration(Aubert, B. et al), Azzolini, V., Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Search for B+ -> l(+)nu(l) recoiling against B- -> D(0)l(-)(nu)over-barX. Phys. Rev. D, 81(5), 051101–9pp.
Abstract: We present a search for the decay B+ -> l(+)nu(l) (l = tau, mu, or e) in (458.9 +/- 5.1) x 10(6) B (B) over bar pairs recorded with the BABAR detector at the PEP-II B-factory. We search for these B decays in a sample of B+B- events where one B- meson is reconstructed as B- -> D(0)l(-)(nu) over barX. Using the method of Feldman and Cousins, we obtain B(B+ -> tau(+)nu(tau)) = (1.7 +/- 0.8 +/- 0.2) x 10(-4), which excludes zero at 2.3 sigma. We interpret the central value in the context of the standard model and find the B meson decay constant to be f(B)(2) = (62 +/- 31) x 10(3) MeV2. We find no evidence for B+ -> e(+)nu(e) and B+ -> mu(+)nu(mu) and set upper limits at the 90% C. L. B(B+ -> e(+)nu(e)) < 0.8 x 10(-5) and B(B+ -> mu(+)nu(mu)) < 1.1 x 10(-5).
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BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Search for B+ meson decay to a(1)(+)(1260)K*(0)(892). Phys. Rev. D, 82(9), 091101–8pp.
Abstract: We present a search for the decay B+ -> a(1)(+)(1260)K*(0)(892). The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, represent 465 X 10(6)B (B) over bar pairs produced in e(+)e(-) annihilation at the energy of the gamma(4S). We find no significant signal and set an upper limit at 90% confidence level on the product of branching fractions B(B+ -> a(1)(+) (1260)K*(0)(892)) X B(a(1)(+)(1260) -> pi(+) pi(-) pi(+)) of 1.8 X 10(-6).
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2020). Search for lepton-flavor-violating decays D-0 -> X(0)e(+/-)mu(-/+). Phys. Rev. D, 101(11), 112003–11pp.
Abstract: We present a search for seven lepton-flavor-violating neutral charm meson decays of the type D-0 -> X(0)e(+/-)mu(-/+), where X-0 represents a pi(0), K-S(0), (K) over bar*(0), rho(0), phi, omega, or eta meson. The analysis is based on 468 fb(-1) of e(+)e(-) annihilation data collected at or close to the Upsilon(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signals are observed, and we establish 90% confidence level upper limits on the branching fractions in the range (5.0-22.5) x 10(-7). The limits are between 1 and 2 orders of magnitude more stringent than previous measurements.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2020). Search for Rare or Forbidden Decays of the D-0 Meson. Phys. Rev. Lett., 124(7), 071802–8pp.
Abstract: We present a search for nine lepton-number-violating and three lepton-flavor-violating neutral charm decays of the type D-0 -> h'(-) h(-) l'(+) l(+) and D-0 -> h'(-) h(+) l'(+/-) l(-/+), where h and h' represent a K or pi meson and l and l' an electron or muon. The analysis is based on 468 fb(-1) of e(+) e(-) annihilation data collected at or close to the Upsilon(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the twelve modes, and we establish 90% confidence level upper limits on the branching fractions in the range (1.0-30.6) x 10(-7). The limits are between 1 and 3 orders of magnitude more stringent than previous measurements.
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