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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2011). Observation of the Baryonic Flavor-Changing Neutral Current Decay Lambda(0)(b) -> Lambda mu(+)mu(-). Phys. Rev. Lett., 107(20), 201802–8pp.
Abstract: We report the first observation of the baryonic flavor-changing neutral current decay Lambda(0)(b) -> Lambda mu(+)mu(-) with 24 signal events and a statistical significance of 5.8 Gaussian standard deviations. This measurement uses a p (p) over bar collisions data sample corresponding to 6.8 fb(-1) at root s = 1.96 TeV collected by the CDF II detector at the Tevatron collider. The total and differential branching ratios for Lambda(0)(b) -> Lambda mu(+)mu(-) are measured. We find B(Lambda(0)(b) -> Lambda mu(+)mu(-)) = [1.73 +/- 0.42(stat) +/- (syst)] x 10(-6). We also report the first measurement of the differential branching ratio of B(s)(0) -> phi mu(+)mu(-), using 49 signal events. In addition, we report branching ratios for B(+) -> K(+)mu(+)mu(-), B(0) -> K(0)mu(+)mu(-), and B -> K*(892)mu(+)mu(-) decays.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2011). Search for a Standard Model Higgs Boson in the H -> ZZ -> l(+)l(-)v(v)over-bar Decay Channel with the ATLAS Detector. Phys. Rev. Lett., 107(22), 221802–18pp.
Abstract: A search for a heavy standard model Higgs boson decaying via H -> ZZ -> l(+)l(-)v (v) over bar, where l = e, mu, is presented. It is based on proton-proton collision data at root s = 7 TeV, collected by the ATLAS experiment at the LHC in the first half of 2011 and corresponding to an integrated luminosity of 1.04 fb(-1). The data are compared to the expected standard model backgrounds. The data and the background expectations are found to be in agreement and upper limits are placed on the Higgs boson production cross section over the entire mass window considered; in particular, the production of a standard model Higgs boson is excluded in the region 340 < m(H) < 450 GeV at the 95% confidence level.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2011). Search for Hadronic Decays of a Light Higgs Boson in the Radiative Decay Gamma -> gamma A(0). Phys. Rev. Lett., 107(22), 221803–7pp.
Abstract: We search for hadronic decays of a light Higgs boson (A(0)) produced in radiative decays of an Gamma(2S) or Gamma(3S) meson, Gamma -> gamma A(0). The data have been recorded by the BABAR experiment at the Gamma(3S) and Gamma(2S) center-of-mass energies and include (121.3 +/- 1.2) x 10(6) Gamma(3S) and (98.3 +/- 0.9) x 10(6) Gamma(2S) mesons. No significant signal is observed. We set 90% confidence level upper limits on the product branching fractions B(Gamma(nS) -> gamma A(0))B(A(0) -> hadrons) (n = 2 or 3) that range from 1 x 10(-6) for an A(0) mass of 0: 3 GeV/c(2) to 8 x 10(-5) at 7 GeV/c(2).
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2011). Search for the Higgs Boson in the H -> WW -> l nu jj Decay Channel in pp Collisions at sqrt(s)=7 TeV with the ATLAS Detector. Phys. Rev. Lett., 107(23), 231801–18pp.
Abstract: A search for a Higgs boson has been performed in the H -> WW -> l nu jj channel in 1.04 fb(-1) of pp collision data at sqrt(s) = 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. No significant excess of events is observed over the expected background and limits on the Higgs boson production cross section are derived for a Higgs boson mass in the range 240 GeV < m(H) < 600 GeV. The best sensitivity is reached for m(H) = 400 GeV, where the 95% confidence level upper bound on the cross section for H -> WW production is 3.1 pb, or 2.7 times the standard model prediction.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2011). Search for a Heavy Particle Decaying into an Electron and a Muon with the ATLAS Detector in sqrt(s)=7 TeV pp collisions at the LHC. Phys. Rev. Lett., 106(25), 251801–18pp.
Abstract: This Letter presents the first search for a heavy particle decaying into an e(+/-)mu(-/+) final state in root s = 7 TeV pp collisions at the LHC. The data were recorded by the ATLAS detector during 2010 and correspond to a total integrated luminosity of 35 pb(-1). No excess above the standard model background expectation is observed. Exclusions at 95% confidence level are placed on two representative models. In an R-parity violating supersymmetric model, tau sneutrinos with a mass below 0.75 TeV are excluded, assuming all R-parity violating couplings are zero except lambda(311)' = 0.11 and lambda(312) = 0.07. In a lepton flavor violating model, a Z'-like vector boson with masses of 0.70-1.00 TeV and corresponding cross sections times branching ratios of 0.175-0.183 pb is excluded. These results extend to higher mass R-parity violating sneutrinos and lepton flavor violating Z's than previous constraints from the Tevatron.
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