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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2012). Search for the Standard Model Higgs boson produced in association with a vector boson and decaying to a b-quark pair with the ATLAS detector. Phys. Lett. B, 718(2), 369–390.
Abstract: This Letter presents the results of a direct search with the ATLAS detector at the LHC for a Standard Model Higgs boson of mass 110 <= m(H) <= 130 GeV produced in association with a W or Z boson and decaying to b (b) over bar. Three decay channels are considered: ZH -> l(+)l(-)b (b) over bar, WH -> lvbb (b) over bar and ZH -> v (v) over bar(b) over bar where l corresponds to an electron or a muon. No evidence for Higgs boson production is observed in a dataset of 7 TeV pp collisions corresponding to 4.7 fb(-1) of integrated luminosity collected by ATLAS in 2011. Exclusion limits on Higgs boson production, at the 95% confidence level, of 2.5 to 5.5 times the Standard Model cross section are obtained in the mass range 110-130 GeV. The expected exclusion limits range between 2.5 and 4.9 for the same mass interval.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2012). Search for the Higgs boson in the H -> WW -> lvjj decay channel at root s=7 TeV with the ATLAS detector. Phys. Lett. B, 718(2), 391–410.
Abstract: A search for the Standard Model Higgs boson has been performed in the H -> WW -> lvjj channel using 4.7 fb(-1) of pp collision data recorded at a centre-of-mass energy of root s = 7 TeV with the ATLAS detector at the Large Hadron Collider. Higgs boson candidates produced in association with zero, one or two jets are included in the analysis to maximize the acceptance for both gluon fusion and weak boson fusion Higgs boson production processes. 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 300 GeV < m(H) < 600 GeV. The best sensitivity is reached for m(H) = 400 GeV, where the observed (expected) 95% confidence level upper bound on the cross section for H -> WW produced in association with zero or one jet is 2.2 pb (1.9 pb), corresponding to 1.9 (1.6) times the Standard Model prediction. In the Higgs boson plus two jets channel, which is more sensitive to the weak boson fusion process, the observed (expected) 95% confidence level upper bound on the cross section for H -> WW production with m(H) = 400 GeV is 0.7 pb (0.6 pb), corresponding to 7.9 (6.5) times the Standard Model prediction.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2012). Search for a Standard Model Higgs boson in the mass range 200-600 GeV in the H -> ZZ -> l(+)l(-)q(q)over-bar decay channel with the ATLAS detector. Phys. Lett. B, 717(1-3), 70–88.
Abstract: A search for a heavy Standard Model Higgs boson decaying via H -> ZZ -> l(+)l(-)q (q) over bar, where l = e or mu, is presented. The search uses a data set of pp collisions at root s = 7 TeV, corresponding to an integrated luminosity of 4.7 fb(-1) collected in 2011 by the ATLAS detector at the CERN LHC. No significant excess of events above the estimated background is found. Upper limits at 95% confidence level on the production cross section of a Higgs boson with a mass in the range between 200 and 600 GeV are derived. A Standard Model Higgs boson with a mass in the range 300 GeV <= m(H) 322 <= GeV or 353 GeV <= m(H) <= 410 GeV is excluded at 95% CL The corresponding expected exclusion range is 351 GeV <= m(H) <= 404 GeV at 95% CL.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2012). Measurement of event shapes at large momentum transfer with the ATLAS detector in pp collisions at root s=7 TeV. Eur. Phys. J. C, 72(11), 2211–22pp.
Abstract: A measurement of event shape variables is presented for large momentum transfer proton-proton collisions using the ATLAS detector at the Large Hadron Collider. Six event shape variables calculated using hadronic jets are studied in inclusive multi-jet events in 35 pb(-1) of integrated luminosity at a center-of-mass energy of root s = 7 TeV. These measurements are compared to predictions by three Monte Carlo event generators containing leading-logarithmic parton showers matched to leading order matrix elements for 2 -> 2 and 2 -> n (n = 2, ... , 6) scattering. Measurements of the third-jet resolution parameter, aplanarity, thrust, sphericity, and transverse sphericity are generally well described. The mean value of each event shape variable is evaluated as a function of the average momentum of the two leading jets p(T,1) and p(T,2), with a mean p(T) approaching 1 TeV.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2012). Search for the Standard Model Higgs boson in the H -> WW(*()) -> lvlv decay mode with 4.7 fb(-1) of ATLAS data at root s=7 TeV. Phys. Lett. B, 716(1), 62–81.
Abstract: A search for the Standard Model Higgs boson in the H -> WW(*()) -> lvlv (l = e.mu) decay mode is presented. The search is performed using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb(-1) at a centre-of-mass energy of 7 TeV collected during 2011 with the ATLAS detector at the Large Hadron Collider. No significant excess of events over the expected background is observed. An upper bound is placed on the Higgs boson production cross section as a function of its mass. A Standard Model Higgs boson with mass in the range between 133 GeV and 261 GeV is excluded at 95% confidence level, while the expected exclusion range is from 127 GeV to 233 GeV. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
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