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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Search for Z* boson at ATLAS detector

We present the results of the search for new excited Z* boson at ATLAS detector in 2011. Results: are based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.9 fb{sup −1} in the dielectron channel and 5.0 fb{sup −1} in the dimuon channel. Since good agreement between experimental data and expectation of the Standard Model is observed in both channels, the existence of Z* is excluded with 95 percent confidence level for all masses below 2.20 TeV. The plans for Z* search in 2012 are discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Semileptonic (lepton, neutrino and jets) WW/WZ resonances searches at √s = 8 and 13 TeV with the ATLAS detector at the LHC

This talk presents the analyses results of the diboson (WW or WZ ) resonances production search in pp collisions at √s = 8 and 13 TeV with the ATLAS detector at the LHC with the semileptonic final state. As benchmark signal models Randall-Sundrum bulk model for KK G* → WW and Heavy Vector Triplet model for W′ → WZ and Z′ → WW are used. No significant excess for diboson resonances production is observed and upper limits on the production cross section times branching fraction of G*, W′ and Z′ are determined at 95% CL.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of polarization angular coefficients in Z boson leptonic decays with ATLAS at the LHC

This paper presents the complete set of polarization angular coefficients A {sub 0−7} describing lepton angular distributions in Z boson decay, which were measured at the ATLAS experiment in proton–proton collisions with the energy √s = 8 TeV. Theoretical values for the difference A {sub 0} − A {sub 2} calculated in the fixed-order QCD perturbation theory O(α{sup 2}{sub s }), demonstrate significant deviation from the measured data, which indicates the necessity of taking into account higher order corrections. The evidence of nonzero coefficients A {sub 5,6,7} was obtained for the first time, in accordance with theoretical calculations in O(α{sup 2}{sub s }) approximation. Measurement of the polarization angular coefficients A {sub i }is important for subsequent precision measurement of parameters of the electroweak model at the LHC, such as the sine of Weinberg electroweak mixing angle sin{sup 2} θ{sub W }and the W boson mass.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Muon and B-physics trigger of the ATLAS experiment in Run 2

This paper presents an overview of muon trigger and B-physics trigger of the ATLAS experiment. Main updates done during the preparation for Run 2 data-taking are outlined. Trigger performance results obtained with new experimental data and modelling are shown.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Electroweak diboson production at ATLAS

This paper is giving an overview of recent ATLAS results on the production cross sections of gauge boson pairs decaying leptonically using data from pp collisions at √s = 13 TeV for ZZ and at √s = 8 TeV for W{sup ±} Z and W{sup ±} W{sup ±} at the LHC at CERN. The cross sections are found to be in agreement with the expectations from the Standard Model within the estimated uncertainties. The production cross section measurements also allow for studies of anomalous triple and quartic gauge couplings for which 95% confidence level limits are set.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

B-meson decays into charmonium states in the ATLAS experiment

The paper presents several recent ATLAS results on the analyses of B-meson decays into charmonium states. These include the measurements of B{sup +} mass and the fractions of J/ψ mesons produced in b-hadron decays in pp collisions at √s = 13 TeV in the center of mass system. The measured partial widths and polarizations in B{sup +}{sub c }→ J/ψD{sup (*)+}{sub s }decays and CP-violation parameters in B{sup 0}{sub s }→ J/ψϕ decays in pp collisions at 7 and 8 TeV in the center of mass system are also presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

New measurements on physics of B-hadrons in ATLAS experiment

Recent results on B-hadron physics in ATLAS are reviewed. A new measurement of CP-violating parameters in B{sub s }→ J/ψφ decay is performed on full Run 1 statistics. Branching fraction BR(B{sub s }→ μ{sup +}μ{sup −}) = (0.9{sup +1.1}{sub −0.8} )×10{sup −9} is measured, below the Standard Model (SM) prediction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurements of the inclusive and differential production cross sections of a top-quark–antiquark pair in association with a Z boson at $\sqrt{s}$ = 13 TeV with the ATLAS detector

Measurements of both the inclusive and differential production cross sections of a top-quark–antiquark pair in association with a Z boson ($t\bar{t}Z$) are presented. The measurements are performed by targeting final states with three or four isolated leptons (electrons or muons) and are based on $\sqrt{s}$=13 TeV proton–proton collision data with an integrated luminosity of 139 fb -1 , recorded from 2015 to 2018 with the ATLAS detector at the CERN Large Hadron Collider. The inclusive cross section is measured to be σ $t\bar{t}Z$ =0.99 ± 0.05 (stat.) ± 0.08 (syst.) pb, in agreement with the most precise theoretical predictions. The differential measurements are presented as a function of a number of kinematic variables which probe the kinematics of the $t\bar{t}Z$ system. Both absolute and normalised differential cross-section measurements are performed at particle and parton levels for specific fiducial volumes and are compared with theoretical predictions at different levels of precision, based on a χ 2 /ndf and p value computation. Overall, good agreement is observed between the unfolded data and the predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Measurement of the associated production of a top-antitop-quark pair and a Higgs boson decaying into a $b\bar{b}$ pair in pp collisions at $\sqrt{s} = 13$ TeV using the ATLAS detector at the LHC

This paper reports the measurement of Higgs boson production in association with a $t\bar{t}$ pair in the $H$ → $b\bar{b}$ decay channel. The analysis uses 140 fb -1 of 13 TeV proton–proton collision data collected with the ATLAS detector at the Large Hadron Collider. The final states with one or two electrons or muons are employed. An excess of events over the expected background is found with an observed (expected) significance of 4.6 (5.4) standard deviations. The $t\bar{t}$ $H$ cross-section is $σ_{t\bar{t} H}$ = $411^{+101}_{-92}$ fb = $411 ± 54$ (stat.) $^{+85}_{-75}$ (syst.) fb for a Higgs boson mass of 125.09 GeV, consistent with the prediction of the Standard Model of $507^{+35}_{-75}$ fb. The cross-section is also measured differentially in bins of the Higgs boson transverse momentum within the simplified template cross-section framework.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Top Quark Mass and Properties Measurements with the ATLAS Detector

The top quark is the heaviest elementary particle and unique among the known quarks since it decays before forming hadronic bound states. This makes measurements of the top quark itself particularly interesting as one can access directly the properties of a bare quark. The latest measurements of these properties with the ATLAS detector are reported using data from 8 TeV and 13 TeV proton-proton collisions at the Large Hadron Collider at CERN. The latest measurements of the top quark mass using template meth- ods, as well as others aiming to measure the mass in a well-de ned scheme, are presented. In addition, measurements for the top quark decay width, top quark spin observables and W-boson helicity in events with top quark pairs ($t\bar{t}$) are presented and compared to the Standard Model predictions. The cross-section measurements of top quark pair production in association with a photon, Z- or W-boson are also reported and compared to the most accurate theoretical calculations. These measurements probe the top quark electroweak couplings. Limits on the rate of avour-changing neutral current processes in the production or decay of the top quark are also shown.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Search for Heavy Higgs Bosons with the ATLAS Detector

The ATLAS experiment at the Large Hadron Collider performed searches for heavy Higgs bosons, whose presence would establish the existance of new physics. Searches for charged and neutral Higgs bosons are carried out using 8 or 13 TeV data for various production modes and in many different final states. No deviations from Standard Model expectations are observed. Exclusions limits are set on the production cross section and on parameters in various benchmark models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Measurements of Cross Sections and Couplings of the Higgs Boson Using the ATLAS Detector

Measurements of cross sections and couplings of the Higgs boson using the ATLAS detector at CERN's LHC are presented. Data from proton proton collisions at $\sqrt{s}$ = 7, 8 and 13 TeV are discussed. A range of production and decay couplings can be tested with a precision that depends on the generality of the assumptions made. Data at 7 and 8 TeV are also combined with CMS results to enhance the precision. The results are all consistent with predictions of the Standard Model..

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Wave Energy Prize - 1/50th Testing - Atlas Ocean Systems Point Absorber

This submission of data includes all the 1/50th scale testing data completed on the Wave Energy Prize for the Atlas Ocean Systems team, and includes: - 1/50th test data (raw & processed) - 1/50th test data video and pictures - 1/50th Test plans and testing documents - SSTF_Submission (summarized results)

1/50th scale↗
DOE OSTI2025

Precision calibration of calorimeter signals in the ATLAS experiment using an uncertainty-aware neural network

The ATLAS experiment at the Large Hadron Collider explores the use of modern neural networks for a multi-dimensional calibration of its calorimeter signal defined by clusters of topologically connected cells (topo-clusters). The Bayesian neural network (BNN) approach not only yields a continuous and smooth calibration function that improves performance relative to the standard calibration but also provides uncertainties on the calibrated energies for each topo-cluster. The results obtained by using a trained BNN are compared to the standard local hadronic calibration and to a calibration provided by training a deep neural network. The uncertainties predicted by the BNN are interpreted in the context of a fractional contribution to the systematic uncertainties of the trained calibration. They are also compared to uncertainty predictions obtained from an alternative estimator employing repulsive ensembles.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

ATLAS Large Scale Thin Gap Chambers

This is a technical scope of work (TSW) between the Fermi National Accelerator Laboratory (Fermilab) and the experimenters of the ATLAS sTGC New Small Wheel collaboration who have committed to participate in beam tests to be carried out during the FY2014 Fermilab Test Beam Facility program.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Analysis of metabolomics datasets with high-performance computing and metabolite atlases

Even with the widespread use of liquid chromatography mass spectrometry (LC/MS) based metabolomics, there are still a number of challenges facing this promising technique. Many, diverse experimental workflows exist; yet there is a lack of infrastructure and systems for tracking and sharing of information. Here, we describe the Metabolite Atlas framework and interface that provides highly-efficient, web-based access to raw mass spectrometry data in concert with assertions about chemicals detected to help address some of these challenges. This integration, by design, enables experimentalists to explore their raw data, specify and refine features annotations such that they can be leveraged for future experiments. Fast queries of the data through the web using SciDB, a parallelized database for high performance computing, make this process operate quickly. Furthermore, by using scripting containers, such as IPython or Jupyter, to analyze the data, scientists can utilize a wide variety of freely available graphing, statistics, and information management resources. In addition, the interfaces facilitate integration with systems biology tools to ultimately link metabolomics data with biological models.

59 BASIC BIOLOGICAL SCIENCES↗