Search for WH production with a light Higgs boson decaying to prompt electron-jets in proton-proton collisions at s\sqrt{s}=7 TeV with the ATLAS detector

A search is performed for WH production with a light Higgs boson decaying to hidden-sector particles resulting in clusters of collimated electrons, known as electron-jets. The search is performed with 2.04 fb-1 of data collected in 2011 with the ATLAS detector at the LHC in proton-proton collisions at $\sqrt{s}$=7 TeV. One event satisfying the signal selection criteria is observed, which is consistent with the expected background rate. Limits on the product of the WH production cross section and the branching ratio of a Higgs boson decaying to prompt electron-jets are calculated as a function of a Higgs boson mass in the range from 100 GeV to 140 GeV.Peer Reviewe

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at root s=7 TeV with the ATLAS detector

"The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of root s = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb(-1). The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 -dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m(jj) < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured b (b) over bar -dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta. RI Gutierrez, Phillip\/C-1161-2011; Ferrando, James\/A-9192-2012; collins-tooth, christopher\/A-9201-2012; Perrino, Roberto\/B-4633-2010; Laurelli, Paolo\/B-1432-2012; De Cecco, Sandro\/B-1016-2012; Stoicea, Gabriel\/B-6717-2011; branchini, paolo\/A-4857-2011; Wolter, Marcin\/A-7412-2012; Rotaru, Marina\/A-3097-2011; O'Shea, Val\/G-1279-2010; Doyle, Anthony\/C-5889-2009; Buttar, Craig\/D-3706-2011; Pina, Joao \/C-4391-2012; Takai, Helio\/C-3301-2012; St.Denis, Richard\/C-8997-2012; Jones, Roger\/H-5578-2011; Britton, David\/F-2602-2010; Li, Xuefei\/C-3861-2012; Fazio, Salvatore \/G-5156-2010; Smirnova, Lidia\/D-8089-2012; Smirnov, Sergei\/F-1014-2011; Gladilin, Leonid\/B-5226-2011; Barreiro, Fernando\/D-9808-2012; Kramarenko, Victor\/E-1781-2012; Prokoshin, Fedor\/E-2795-2012; Alexa, Calin\/F-6345-2010; Pacheco Pages, Andres\/C-5353-2011; Moorhead, Gareth\/B-6634-2009; Livan, Michele\/D-7531-2012; Petrucci, Fabrizio\/G-8348-2012; Wemans, Andre\/A-6738-2012; Fabbri, Laura\/H-3442-2012; Kurashige, Hisaya\/H-4916-2012; Villa, Mauro\/C-9883-2009; Kuzhir, Polina\/H-8653-2012; Delmastro, Marco\/I-5599-2012