Searches for both resonant and nonresonant Higgs boson pair production are performed in the hh→bbττ, γγWW* final states using 20.3 fb−1 of pp collision data at a center-of-mass energy of 8 TeV recorded with the ...
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Searches for both resonant and nonresonant Higgs boson pair production are performed in the hh→bbττ, γγWW* final states using 20.3 fb−1 of pp collision data at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the Large Hadron Collider. No evidence of their production is observed and 95% confidence-level upper limits on the production cross sections are set. These results are then combined with the published results of the hh→γγbb, bbbb analyses. An upper limit of 0.69 (0.47) pb on the nonresonant hh production is observed (expected), corresponding to 70 (48) times the SM gg→hh cross section. For production via narrow resonances, cross-section limits of hh production from a heavy Higgs boson decay are set as a function of the heavy Higgs boson mass. The observed (expected) limits range from 2.1 (1.1) pb at 260 GeV to 0.011 (0.018) pb at 1000 GeV. These results are interpreted in the context of two simplified scenarios of the Minimal Supersymmetric Standard Model.
A search is presented for pair production of a new heavy quark (Q) that decays into a W boson and a light quark (q) in the final state where one W boson decays leptonically (to an electron or muon plus a neutrino) and...
A search is presented for pair production of a new heavy quark (Q) that decays into a W boson and a light quark (q) in the final state where one W boson decays leptonically (to an electron or muon plus a neutrino) and the other W boson decays hadronically. The analysis is performed using an integrated luminosity of 20.3 fb−1 of pp collisions at s=8 TeV collected by the ATLAS detector at the LHC. No evidence of QQ¯ production is observed. New chiral quarks with masses below 690 GeV are excluded at 95% confidence level, assuming bR(Q→Wq)=1. Results are also interpreted in the context of vectorlike quark models, resulting in the limits on the mass of a vectorlike quark in the two-dimensional plane of bR(Q→Wq) versus bR(Q→Hq).
It was found that the non-perturbative corrections calculated using Pythia with the Perugia 2011 tune did not include the effect of the underlying event. The affected correction factors were recomputed using the Pythi...
It was found that the non-perturbative corrections calculated using Pythia with the Perugia 2011 tune did not include the effect of the underlying event. The affected correction factors were recomputed using the Pythia 6.427 generator. These corrections are applied as baseline to the NLO pQCD calculations and thus the central values of the theoretical predictions have changed by a few percent with the new corrections. This has a minor impact on the agreement between the data and the theoretical predictions. Figures 2 and 6 to 13, and all the tables have been updated with the new values. A few sentences in the discussion in sections 5.2 and 9 were altered or removed.
Inverted pendulum system is a nonlinear multivariable system which is inherently unstable. It requires designing of a hybrid controller which can adapt in different disturbance conditions and work appreciably well whe...
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Inverted pendulum system is a nonlinear multivariable system which is inherently unstable. It requires designing of a hybrid controller which can adapt in different disturbance conditions and work appreciably well when compared to conventional controllers. In this paper, a hybrid controller for inverted pendulum is designed. Initially Fuzzy and LQR controllers for inverted pendulum are designed, then data are collected from these controllers, which then are used to train Adaptive neuro-fuzzy inference system (ANFIS). This hybrid controller has advantages of Fuzzy, LQR controllers and of neural networks; so it gives better performance.
Searches are performed for resonant and nonresonant Higgs boson pair production in the γγbb¯ final state using 20 fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV recorded with the ATLAS de...
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Searches are performed for resonant and nonresonant Higgs boson pair production in the γγbb¯ final state using 20 fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the CERN Large Hadron Collider. A 95% confidence level upper limit on the cross section times branching ratio of nonresonant production is set at 2.2 pb, while the expected limit is 1.0 pb. The difference derives from a modest excess of events, corresponding to 2.4 standard deviations from the background-only hypothesis. The limit observed in the search for a narrow X→hh resonance ranges between 0.7 and 3.5 pb as a function of the resonance mass.
Measurements of inclusive jet production are performed in pp and Pb+Pb collisions at sNN=2.76 TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 and 0.14 nb−1, respectively. The ...
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Measurements of inclusive jet production are performed in pp and Pb+Pb collisions at sNN=2.76 TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 and 0.14 nb−1, respectively. The jets are identified with the anti-kt algorithm with R=0.4, and the spectra are measured over the kinematic range of jet transverse momentum 32bsolute rapidity |y|<2.1 and as a function of collision centrality. The nuclear modification factor RAA is evaluated, and jets are found to be suppressed by approximately a factor of 2 in central collisions compared to pp collisions. The RAA shows a slight increase with pT and no significant variation with rapidity.
A measurement of spin correlation in tt¯ production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, correspo...
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A measurement of spin correlation in tt¯ production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb−1. The correlation between the top and antitop quark spins is extracted from dilepton tt¯ events by using the difference in the azimuthal angle between the two charged leptons in the laboratory frame. In the helicity basis the measured degree of correlation corresponds to Ahelicity=0.38±0.04, in agreement with the standard model prediction. A search is performed for pair production of top squarks with masses close to the top quark mass decaying to predominantly right-handed top quarks and a light neutralino, the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 191 GeV are excluded at the 95% confidence level.
Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3 fb−1 of pp collisions produced by the Large Hadron Collider at a center-of-mass energy of s=8 TeV and reco...
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Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3 fb−1 of pp collisions produced by the Large Hadron Collider at a center-of-mass energy of s=8 TeV and recorded by the ATLAS detector. Cross sections are obtained from measured H→γγ and H→ZZ*→4ℓ event yields, which are combined accounting for detector efficiencies, fiducial acceptances, and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, number of jets in the event, and transverse momentum of the leading jet. The total production cross section is determined to be σpp→H=33.0±5.3 (stat)±1.6 (syst) pb. The measurements are compared to state-of-the-art predictions.
A search for new phenomena in LHC proton-proton collisions at a center-of-mass energy of s=8 TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb−1. The angular distributions are studi...
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A search for new phenomena in LHC proton-proton collisions at a center-of-mass energy of s=8 TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb−1. The angular distributions are studied in events with at least two jets; the highest dijet mass observed is 5.5 TeV. All angular distributions are consistent with the predictions of the standard model. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario is excluded at 95% C.L.; median expected limits are 8.9 TeV for the destructive interference scenario and 14.1 TeV for the constructive interference scenario.
This Letter reports evidence of triple gauge boson production pp→W(ℓν)γγ+X, which is accessible for the first time with the 8 TeV LHC data set. The fiducial cross section for this process is measured in a data sam...
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This Letter reports evidence of triple gauge boson production pp→W(ℓν)γγ+X, which is accessible for the first time with the 8 TeV LHC data set. The fiducial cross section for this process is measured in a data sample corresponding to an integrated luminosity of 20.3 fb−1, collected by the ATLAS detector in 2012. Events are selected using the W boson decay to eν or μν as well as requiring two isolated photons. The measured cross section is used to set limits on anomalous quartic gauge couplings in the high diphoton mass region.
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