Search for the Standard Model Higgs boson decay to mu(+)mu(-) with the ATLAS detector
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Engineering topics
Anger, P.
Publications and source records attributed to Anger, P..
Fiducial and differential cross sections of Higgs boson production measured in the four-lepton decay channel in pp collisions at root s=8 TeV with the ATLAS detector
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Search for new resonances in W gamma and Z gamma final states in pp collisions at root s=8 TeV with the ATLAS detector
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Measurement of the cross section of high transverse momentum Z → b b ¯ production in proton–proton collisions at s = 8 TeV with the ATLAS detector
Not Available
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Measurement of differential production cross-sections for a Z boson in association with b-jets in 7 TeV proton-proton collisions with the ATLAS detector
We report measurements of differential production cross-sections of a Z boson in association with b-jets in pp collisions at √ s = 7 TeV. The data analysed correspond to an integrated luminosity of 4.6 fb -1 recorded with the ATLAS detector at the Large Hadron Collider. Particle-level cross-sections are determined for events with a Z boson decaying into an electron or muon pair, and containing b-jets. For events with at least one b-jet, the cross-section is presented as a function of the Z boson transverse momentum and rapidity, together with the inclusive b-jet cross-section as a function of b-jet transverse momentum, rapidity and angular separations between the b-jet and the Z boson. For events with at least two b-jets, the cross-section is determined as a function of the invariant mass and angular separation of the two highest transverse momentum b-jets, and as a function of the Z boson transverse momentum and rapidity. Lastly, results are compared to leading-order and next-to-leading-order perturbative QCD calculations.
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Search for the lepton flavor violating decay Z → e μ in p p collisions at s = 8 TeV with the ATLAS detector
Not Available
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Search for Scalar Diphoton Resonances in the Mass Range 65–600 GeV with the ATLAS Detector in p p Collision Data at s = 8 TeV
Not Available
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Search for the direct production of charginos, neutralinos and staus in final states with at least two hadronically decaying taus and missing transverse momentum in pp collisions at $ \sqrt{s}=8 $ TeV with the ATLAS detector
We present results of a search for the electroweak associated production of charginos and next-to-lightest neutralinos, pairs of charginos or pairs of tau sleptons. These processes are characterised by final states with at least two hadronically decaying tau leptons, missing transverse momentum and low jet activity. The analysis is based on an integrated luminosity of 20.3 fb ₋1 of proton-proton collisions at √s = 8TeV recorded with the ATLAS experiment at the Large Hadron Collider. We observed no significant excess with respect to the predictions from Standard Model processes. Limits are set at 95% confidence level on the masses of the lighter chargino and next-to-lightest neutralino for various hypotheses for the lightest neutralino mass in simplified models. In the scenario of direct production of chargino pairs, with each chargino decaying into the lightest neutralino via an intermediate tau slepton, chargino masses up to 345 GeV are excluded for a massless lightest neutralino. For associated production of mass-degenerate charginos and next-tolightest neutralinos, both decaying into the lightest neutralino via an intermediate tau slepton, masses up to 410 GeV are excluded for a massless lightest neutralino.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurements of normalized differential cross sections for t t ¯ production in p p collisions at ( s ) = 7 TeV using the ATLAS detector
We present measurements of normalized differential cross sections for top-quark pair production as a function of the top-quark transverse momentum, and of the mass, transverse momentum, and rapidity of the $t\bar{t}$ system, in proton–proton collisions at a center-of-mass energy of √ s=7 TeV. The data set corresponds to an integrated luminosity of 4.6 fb ₋1 , recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Events are selected in the lepton + jets channel, requiring exactly one lepton and at least four jets with at least one of the jets tagged as originating from a b-quark. The measured spectra are corrected for detector efficiency and resolution effects and are compared to several Monte Carlo simulations and theory calculations. The results are in fair agreement with the predictions in a wide kinematic range. Nevertheless, data distributions are softer than predicted for higher values of the mass of the $t\bar{t}$ system and of the top-quark transverse momentum. Lastly, the measurements can also discriminate among different sets of parton distribution functions.
43 PARTICLE ACCELERATORS↗
Measurement of long-range pseudorapidity correlations and azimuthal harmonics in s N N = 5.02 TeV proton-lead collisions with the ATLAS detector
We present measurements of two-particle correlation functions and the first five azimuthal harmonics, v 1 to v 5 , are presented, using 28 nb -1 of p + Pb collisions at a nucleon-nucleon center-of-mass energy of s N N = 5.02 TeV measured with the ATLAS detector at the LHC. Significant long-range "ridgelike" correlations are observed for pairs with small (|Δϕ|<π/3) and back-to-back pairs (|Δϕ|>2π/3) over the transverse momentum range 0.44 GeV. The ν 2 ( p T ), ν 3 ( p T ), and ν 4 ( p T ) are compared to the ν n coefficients in Pb+Pb collisions at s N N = 2.76 TeV with similar event multiplicities. Reasonable agreement is observed after accounting for the difference in the average p T of particles produced in the two collision systems.
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Search for WZ resonances in the fully leptonic channel using pp collisions at root s=8 TeV with the ATLAS detector
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Search for strong production of supersymmetric particles in final states with missing transverse momentum and at least three b-jets at $$ \sqrt{s} = 8 $$ TeV proton-proton collisions with the ATLAS detector
We report the results of a search for strong production of supersymmetric particles in 20.1 fb ₋1 of proton-proton collisions at a centre-of-mass energy of 8TeV using the ATLAS detector at the LHC. The search is performed separately in events with either zero or at least one high-p T lepton (electron or muon), large missing transverse momentum, high jet multiplicity and at least three jets identified as originated from the fragmentation of a b-quark. No excess is observed with respect to the Standard Model predictions. The results are interpreted in the context of several supersymmetric models involving gluinos and scalar top and bottom quarks, as well as a mSUGRA/CMSSM model. Lastly, gluino masses up to 1340 GeV are excluded, depending on the model, significantly extending the previous ATLAS limits.
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Evidence for Electroweak Production of W ± W ± j j in p p Collisions at s = 8 TeV with the ATLAS Detector
Not Available
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Electron and photon energy calibration with the ATLAS detector using LHC Run 1 data
This paper presents the electron and photon energy calibration achieved with the ATLAS detector using about 25 fb -1 of LHC proton–proton collision data taken at centre-of-mass energies of √s=7 and 8 TeV. The reconstruction of electron and photon energies is optimised using multivariate algorithms. The response of the calorimeter layers is equalised in data and simulation, and the longitudinal profile of the electromagnetic showers is exploited to estimate the passive material in front of the calorimeter and reoptimise the detector simulation. After all corrections, the Z resonance is used to set the absolute energy scale. For electrons from Z decays, the achieved calibration is typically accurate to 0.05 % in most of the detector acceptance, rising to 0.2 % in regions with large amounts of passive material. The remaining inaccuracy is less than 0.2–1 % for electrons with a transverse energy of 10 GeV, and is on average 0.3 % for photons. The detector resolution is determined with a relative inaccuracy of less than 10 % for electrons and photons up to 60 GeV transverse energy, rising to 40 % for transverse energies above 500 GeV.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using $\sqrt{s}=8 $ TeV proton-proton collision data
A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in $ \sqrt{s} $ = 8 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb -1 . Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A 0 = -2m 0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the Z/γ* boson transverse momentum distribution in pp collisions at $ \sqrt{s}=7 $ TeV with the ATLAS detector
This paper describes a measurement of the Z/γ* boson transverse momentum spectrum using ATLAS proton-proton collision data at a centre-of-mass energy of (Formula presented) TeV at the LHC. The measurement is performed in the Z/γ*→ e + e - and Z/γ*→ μ + μ - channels, using data corresponding to an integrated luminosity of 4.7 fb -1 . Normalized differential cross sections as a function of the Z/γ* boson transverse momentum are measured for transverse momenta up to 800 GeV. The measurement is performed inclusively for Z/γ* rapidities up to 2.4, as well as in three rapidity bins. The channel results are combined, compared to perturbative and resummed QCD calculations and used to constrain the parton shower parameters of Monte Carlo generators.
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Search for pair-produced third-generation squarks decaying via charm quarks or in compressed supersymmetric scenarios in p p collisions at s = 8 TeV with the ATLAS detector
Results of a search for supersymmetry via direct production of third-generation squarks are reported, using 20.3 fb -1 of proton-proton collision data at $ \sqrt{s} $=8 TeV recorded by the ATLAS experiment at the LHC in 2012. Two different analysis strategies based on monojetlike and c-tagged event selections are carried out to optimize the sensitivity for direct top squark-pair production in the decay channel to a charm quark and the lightest neutralino ($ \tilde{t} $ -1 →c+ $ \tilde{χ} ^0_1 $) across the top squark-neutralino mass parameter space. No excess above the Standard Model background expectation is observed. The results are interpreted in the context of direct pair production of top squarks and presented in terms of exclusion limits in the (m $ \tilde{t} $ -1 , m $ \tilde{χ} ^0_1 $ ) parameter space. A top squark of mass up to about 240 GeV is excluded at 95% confidence level for arbitrary neutralino masses, within the kinematic boundaries. Top squark masses up to 270 GeV are excluded for a neutralino mass of 200 GeV. In a scenario where the top squark and the lightest neutralino are nearly degenerate in mass, top squark masses up to 260 GeV are excluded. The results from the monojetlike analysis are also interpreted in terms of compressed scenarios for top squark-pair production in the decay channel $ \tilde{t} $ -1 → b + ff' +$ \tilde{χ} ^0_1 $ and sbottom pair production with $ \tilde{b} $ 1 → b +$ \tilde{χ} ^0_1 $, leading to a similar exclusion for nearly mass-degenerate third-generation squarks and the lightest neutralino. The results in this paper significantly extend previous results at colliders.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Flavor tagged time-dependent angular analysis of the B s 0 → J / ψ ϕ decay and extraction of Δ Γ s and the weak phase ϕ s in ATLAS
A measurement of the B$ ^0_s $ →J/ψφ decay parameters, updated to include flavor tagging is reported using 4.9 fb -1 of integrated luminosity collected by the ATLAS detector from $ \sqrt{s} $=7 TeV pp collisions recorded in 2011 at the LHC. The values measured for the physical parameters are ϕ s =0.12±0.25(stat)±0.05(syst)rad ΔΓ s =0.053±0.021(stat)±0.010(syst)ps -1 Γ s =0.677±0.007(stat)±0.004(syst)ps -1 |A (0)| 2 =0.220±0.008(stat)±0.009(syst) |A0(0)| 2 =0.529±0.006(stat)±0.012(syst) δ ⊥ =3.89±0.47(stat)±0.11(syst)rad where the parameter ΔΓ s is constrained to be positive. The S-wave contribution was measured and found to be compatible with zero. Results for ϕ s and ΔΓ s are also presented as 68% and 95% likelihood contours, which show agreement with the Standard Model expectations.
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