Search for supersymmetry in final states with jets, missing transverse momentum and one isolated lepton in s = 7 TeV pp collisions using 1 fb − 1 of ATLAS data
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Engineering topics
Alexander, G.
Publications and source records attributed to Alexander, G..
Measurement of the isolated diphoton cross section in p p collisions at s = 7 TeV with the ATLAS detector
Here, the ATLAS experiment has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at √s = 7 TeV. The full data set acquired in 2010 is used, corresponding to an integrated luminosity of 37 pb –1 . The background, consisting of hadronic jets and isolated electrons, is estimated with fully data-driven techniques and subtracted. The differential cross sections, as functions of the di-photon mass (m γγ ), total transverse momentum (pT, γγ ), and azimuthal separation (ΔΦ γγ ), are presented and compared to the predictions of next-to-leading-order QCD.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Search for a heavy Standard Model Higgs boson in the channel H → Z Z → ℓ ⁺ ℓ ⁻ q q ¯ using the ATLAS detector
A search for a heavy Standard Model Higgs boson decaying via H → ZZ → ℓ⁺ℓ⁻qq¯, where ℓ = e,μ, is presented. The search is performed using a data set of pp collisions at √s = 7 TeV, corresponding to an integrated luminosity of 1.04 fb⁻¹ collected in 2011 by the ATLAS detector at the CERN LHC collider. No significant excess of events above the estimated background is found. Upper limits at 95% confidence level on the production cross section (relative to that expected from the Standard Model) of a Higgs boson with a mass in the range between 200 and 600 GeV are derived. Within this mass range, there is at present insufficient sensitivity to exclude a Standard Model Higgs boson. For a Higgs boson with a mass of 360 GeV, where the sensitivity is maximal, the observed and expected cross section upper limits are factors of 1.7 and 2.7, respectively, larger than the Standard Model prediction.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the W → τ ν τ cross section in pp collisions at s = 7 TeV with the ATLAS experiment
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the cross-section for b-jets produced in association with a Z boson at s = 7 TeV with the ATLAS detector
Not Available
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Search for Dilepton Resonances in pp Collisions at {radical}(s)=7 TeV with the ATLAS Detector
This Letter reports on a search for narrow high-mass resonances decaying into dilepton final states. The data were recorded by the ATLAS experiment in pp collisions at {radical}(s)=7 TeV at the Large Hadron Collider and correspond to a total integrated luminosity of 1.08 (1.21) fb{sup -1} in the e{sup +}e{sup -} ({mu}{sup +}{mu}{sup -}) channel. No statistically significant excess above the standard model expectation is observed and upper limits are set at the 95% C.L. on the cross section times branching fraction of Z{sup '} resonances and Randall-Sundrum gravitons decaying into dileptons as a function of the resonance mass. A lower mass limit of 1.83 TeV on the sequential standard model Z{sup '} boson is set. A Randall-Sundrum graviton with coupling k/M{sub Pl}=0.1 is excluded at 95% C.L. for masses below 1.63 TeV.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for massive colored scalars in four-jet final states in $\sqrt{s}=7~\mbox{TeV}$ proton–proton collisions with the ATLAS detector
A search for pair-produced scalar particles decaying to a four-jet final state is presented. The analysis is performed using an integrated luminosity of 34 pb -1 recorded by the ATLAS detector in 2010. No deviation from the Standard Model is observed. For a scalar mass of 100 GeV (190 GeV) the limit on the scalar gluon pair production cross section at 95% confidence level is 1 nb (0.28 nb). When these results are interpreted as mass limits, scalar-gluons (hyperpions) with masses of 100 to 185 GeV (100 to 155 GeV) are excluded at 95% confidence level with the exception of a mass window of width about 5 GeV (15 GeV) around 140 GeV.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the Z → τ τ cross section with the ATLAS detector
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for a heavy neutral particle decaying into an electron and a muon using 1 fb -1 of ATLAS data
A search is presented for a high mass neutral particle that decays directly to the e < sup > ± < /sup > μ < sup > ∓ < /sup > final state. The data sample was recorded by the ATLAS detector in √ s = 7 TeV pp collisions at the LHC from March to June 2011 and corresponds to an integrated luminosity of 1.07 fb < sup > -1 < /sup > . The data are found to be consistent with the Standard Model background. The high e < sup > ± < /sup > μ < sup > ∓ < /sup > mass region is used to set 95% confidence level upper limits on the production of two possible new physics processes: tau sneutrinos in an R-parity violating supersymmetric model and Z'-like vector bosons in a lepton flavor violating model.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the inclusive isolated prompt photon cross-section in pp collisions at root s=7 TeV using 35 pb(-1) of ATLAS data
A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy {radical}s = 7 TeV is presented. The measurement covers the pseudorapidity ranges |{eta}| < 1.37 and 1.52 {le} |{eta}| < 2.37 in the transverse energy range 45 {le} E{sub T} < 400 GeV. The results are based on an integrated luminosity of 35 pb{sup -1}, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Search for the Higgs Boson in the H{yields}WW{yields}l{nu}jj Decay Channel in pp Collisions at {radical}(s)=7 TeV with the ATLAS Detector
A search for a Higgs boson has been performed in the H{yields}WW{yields}l{nu}jj channel in 1.04 fb{sup -1} of pp collision data at {radical}(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{sub H}<600 GeV. The best sensitivity is reached for m{sub H}=400 GeV, where the 95% confidence level upper bound on the cross section for H{yields}WW production is 3.1 pb, or 2.7 times the standard model prediction.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at $\sqrt{s}=7\mbox{~TeV}$ 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 s√=7~TeVs=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 T <400 GeV and rapidity in the range |y|<2.1. The $b\bar{b}$ -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 χ in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Finally, 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 $b\bar{b}$-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the jet fragmentation function and transverse profile in proton–proton collisions at a center-of-mass energy of 7 TeV with the ATLAS detector
The jet fragmentation function and transverse profile for jets with 25 GeV < p T jet < 500 GeV and |η jet | < 1.2 produced in proton–proton collisions with a center-of-mass energy of 7 TeV are presented. The measurement is performed using data with an integrated luminosity of 36 pb –1 . Jets are reconstructed and their momentum measured using calorimetric information. The momenta of the charged particle constituents are measured using the tracking system. The distributions corrected for detector effects are compared with various Monte Carlo event generators and generator tunes. Several of these choices show good agreement with the measured fragmentation function. Furthermore, none of these choices reproduce both the transverse profile and fragmentation function over the full kinematic range of the measurement.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for new phenomena in final states with large jet multiplicities and missing transverse momentum using $\sqrt {s}$ = 7 TeV pp collisions with the ATLAS detector
Results are presented of a search for any particle(s) decaying to six or more jets in association with missing transverse momentum. The search is performed using 1.34 fb -1 of $\sqrt {s}$ = 7 TeV proton-proton collisions recorded by the ATLAS detector during 2011. Data-driven techniques are used to determine the backgrounds in kinematic regions that require at least six, seven or eight jets, well beyond the multiplicities required in previous analyses. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a supersymmetry model (MSUGRA/CMSSM) where they extend previous constraints.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for new phenomena with the monojet and missing transverse momentum signature using the ATLAS detector in root s=7 TeV proton-proton collisions
A search for new phenomena in events featuring a high energy jet and large missing transverse momentum in proton-proton collisions at {radical}s = 7 TeV is presented using a dataset corresponding to an integrated luminosity of 33 pb{sup -1} recorded with the ATLAS detector at the Large Hadron Collider. The number of observed events is consistent with the Standard Model prediction. This result is interpreted in terms of limits on a model of Large Extra Dimensions.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of multi-jet cross sections in proton–proton collisions at a 7 TeV center-of-mass energy
Inclusive multi-jet production is studied in proton–proton collisions at a center-of-mass energy of 7 TeV, using the ATLAS detector. The data sample corresponds to an integrated luminosity of 2.4 pb -1 . Results on multi-jet cross sections are presented and compared to both leading-order plus parton-shower Monte Carlo predictions and to next-to-leading-order QCD calculations.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for neutral MSSM Higgs bosons decaying to tau(+)tau(-) pairs in proton-proton collisions root s=7 TeV with the ATLAS detector
A search for neutral Higgs bosons decaying to pairs of {tau} leptons with the ATLAS detector at the LHC is presented. The analysis is based on proton-proton collisions at a center-of-mass energy of 7 TeV, recorded in 2010 and corresponding to an integrated luminosity of 36 pb{sup -1}. After signal selection, 276 events are observed in this data sample. The observed number of events is consistent with the total expected background of 269 {+-} 36 events. Exclusion limits at the 95% confidence level are derived for the production cross section of a generic Higgs boson {phi} as a function of the Higgs boson mass and for A/H/h production in the Minimal Supersymmetric Standard Model (MSSM) as a function of the parameters m{sub A} and tan {beta}.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗