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Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at $\sqrt{s} = 7\ \mbox{TeV}$ with the ATLAS experiment
This paper describes an analysis of the angular distribution of W→eν and W→μν decays, using data from pp collisions at √s =7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb -1 . Using the decay lepton transverse momentum and the missing transverse momentum, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f 0 ,f L and f R over two ranges of W transverse momentum (p$W\atop{T}$): 35 < p$W\atop{T}$ < 50 GeV and p$W\atop{T}$ > 50 GeV. Good agreement is found with theoretical predictions. For p W T > 50 GeV, the values of f 0 and f L -f R , averaged over charge and lepton flavour, are measured to be: f 0 =0.127±0.030±0.108 and f L -f R =0.252±0.017±0.030, where the first uncertainties are statistical, and the second include all systematic effects.
Measurements of the Higgs boson production and decay rates and coupling strengths using pp collision data at $\sqrt{s} = 7$ and 8 TeV in the ATLAS experiment
Combined analyses of the Higgs boson production and decay rates as well as its coupling strengths to vector bosons and fermions are presented. The combinations include the results of the analyses of the H → γγ,ZZ*,WW*,Zγ, $b\bar{b}$,ττ and μμ decay modes, and the constraints on the associated production with a pair of top quarks and on the off-shell coupling strengths of the Higgs boson. The results are based on the LHC proton-proton collision datasets, with integrated luminosities of up to 4.7 fb- 1 at s√ = 7 TeV and 20.3 fb -1 at s√ = 8 TeV, recorded by the ATLAS detector in 2011 and 2012. Combining all production modes and decay channels, the measured signal yield, normalised to the Standard Model expectation, is 1.18 +0.15 -0.14 . The observed Higgs boson production and decay rates are interpreted in a leading-order coupling framework, exploring a wide range of benchmark coupling models both with and without assumptions on the Higgs boson width and on the Standard Model particle content in loop processes. The data are found to be compatible with the Standard Model expectations for a Higgs boson at a mass of 125.36 GeV for all models considered.
Reconstruction of hadronic decay products of tau leptons with the ATLAS experiment
This document presents a new method of reconstructing the individual charged and neutral hadrons in tau decays with the ATLAS detector. The reconstructed hadrons are used to classify the decay mode and to calculate the visible four-momentum of reconstructed tau candidates, significantly improving the resolution with respect to the calibration in the existing tau reconstruction. The performance of the reconstruction algorithm is optimised and evaluated using simulation and validated using samples of Z → ττ and Z(→ μμ)+jets events selected from proton–proton collisions at a centre-of-mass energy √s = 8 TeV, corresponding to an integrated luminosity of 5 fb -1 .
Study of $WW\gamma $ and $WZ\gamma $ production in $pp$ collisions at $\sqrt{s} = {8} \,{\text {TeV}}$ and search for anomalous quartic gauge couplings with the ATLAS experiment
This paper presents a study of WWγ and WZγ triboson production using events from proton–proton collisions at a centre-of-mass energy of √s = 8 TeV recorded with the ATLAS detector at the LHC and corresponding to an integrated luminosity of 20.2 fb –1 . The WWγ production cross-section is determined using a final state containing an electron, a muon, a photon, and neutrinos (eνμνγ). Upper limits on the production cross-section of the eνμνγ final state and the WWγ and WZγ final states containing an electron or a muon, two jets, a photon, and a neutrino (eνjjγ or μνjjγ) are also derived. The results are compared to the cross-sections predicted by the Standard Model at next-to-leading order in the strong-coupling constant. In addition, upper limits on the production cross-sections are derived in a fiducial region optimised for a search for new physics beyond the Standard Model. The results are interpreted in the context of anomalous quartic gauge couplings using an effective field theory. Confidence intervals at 95% confidence level are derived for the 14 coupling coefficients to which WWγ and WZγ production are sensitive.
Prompt and non-prompt $J/\psi $ and $\psi (2\mathrm {S})$ suppression at high transverse momentum in $5.02~\mathrm {TeV}$ Pb+Pb collisions with the ATLAS experiment
CERN for the benefit of the ATLAS collaboration. A measurement of $J/\psi $ and $\psi (2\mathrm {S})$ production is presented. It is based on a data sample from Pb+Pb collisions at s NN =5.02 TeV and pp collisions at $ \sqrt{s}$=5.02 TeV recorded by the ATLAS detector at the LHC in 2015, corresponding to an integrated luminosity of 0.42 nb -1 and 25 pb -1 in Pb+Pb and pp, respectively. The measurements of per-event yields, nuclear modification factors, and non-prompt fractions are performed in the dimuon decay channel for 9 < p$\mathbb μμ\atop{T}$ < 40 GeV in dimuon transverse momentum, and -2 < y μμ < 2 in rapidity. Strong suppression is found in Pb+Pb collisions for both prompt and non-prompt $J/\psi $, increasing with event centrality. The suppression of prompt $\psi (2\mathrm {S})$ is observed to be stronger than that of $J/\psi $, while the suppression of non-prompt $\psi (2\mathrm {S})$ is equal to that of the non-prompt $J/\psi $ within uncertainties, consistent with the expectation that both arise from b-quarks propagating through the medium. Despite prompt and non-prompt $J/\psi $ arising from different mechanisms, the dependence of their nuclear modification factors on centrality is found to be quite similar.
Measurement of colour flow using jet-pull observables in $t\bar{t}$ events with the ATLAS experiment at $\sqrt{s} = 13\,\hbox {TeV}$
Previous studies have shown that weighted angular moments derived from jet constituents encode the colour connections between partons that seed the jets. This paper presents measurements of two such distributions, the jet-pull angle and jet-pull magnitude, both of which are derived from the jet-pull angular moment. The measurement is performed in $t\bar{t}$ events with one leptonically decaying W boson and one hadronically decaying W boson, using 36.1fb -1 of pp collision data recorded by the ATLAS detector at s√=13 TeV delivered by the Large Hadron Collider. The observables are measured for two dijet systems, corresponding to the colour-connected daughters of the W boson and the two b-jets from the top-quark decays, which are not expected to be colour connected. To allow the comparison of the measured distributions to colour model predictions, the measured distributions are unfolded to particle level, after correcting for experimental effects introduced by the detector. While good agreement can be found for some combinations of predictions and observables, none of the predictions describes the data well across all observables.
Electron reconstruction and identification in the ATLAS experiment using the 2015 and 2016 LHC proton-proton collision data at s√ = 13 TeV
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Experiments and Thermodynamic Modeling of Chukanovite (Fe2(OH)2CO3) to High Ionic Strengths.
Abstract not provided.
National Criticality Experiments Research Center: Capabilities and Experiments
Abstract not provided.
Nucleon Decay and Neutrino Experiments, Experiments at High Energy Hadron Colliders, and String Theory
This is the final report of the DOE grant DEFG0292ER40697 that supported the research activities of the Stony Brook High Energy Physics Group from November 15, 1991 to April 30, 2013. During the grant period, the grant supported the research of three Stony Brook particle physics research groups: The Nucleon Decay and Neutrino group, the Hadron Collider Group, and the Theory Group.
Progress Report on Disassembly and Post-Irradiation Experiments for UCSB ATR-2 Experiment
The reactor pressure vessel (RPV) in a light-water reactor (LWR) represents the first line of defense against a release of radiation in case of an accident. Thus, regulations that govern the operation of commercial nuclear power plants require conservative margins of fracture toughness, both during normal operation and under accident scenarios. In the unirradiated condition, the RPV has sufficient fracture toughness such that failure is implausible under any postulated condition, including pressurized thermal shock (PTS) in pressurized water reactors (PWR). In the irradiated condition, however, the fracture toughness of the RPV may be severely degraded, with the degree of toughness loss dependent on the radiation sensitivity of the materials. As stated in previous progress reports, the available embrittlement predictive models, e.g. [1], and our present understanding of radiation damage are not fully quantitative, and do not treat all potentially significant variables and issues, particularly considering extension of operation to 80y.
Dynamic Initiator Experiments using IMPULSE (Impact System for Ultrafast Synchrotron Experiments) at the Advanced Photon Source
New dynamic imaging capabilities at the Advanced Photon Source.
Source Physics Experiment Phase II, Dry Alluvium Geology (DAG) Experiments Using Nitromethane
Need to provide briefing to the State of Nevada as part of the Permitting process for the Nevada Chemical Accident Prevention Program (CAPP) for use of nitromethane at the NNSS. This document will be accessible to the public as part of the CAPP program.
Measurement of $W$ -Boson Helicity-Fractions in Top-Quark Decays with the CDF II Experiment and Prospects for an Early $t\overline{t}$ Cross-Section Measurement with the CMS Experiment
Aus was besteht die Welt? Die Frage nach den fundamentalen Bausteinen der Materie beschaftigte Wissenschaftler und Gelehrte zu allen Zeiten. Ausgehend von abstrakten philosophischen Uberlegungen wurde das Konzept von kleinsten, nicht weiter zerteilbaren Grundbausteinen der Materie bereits einige Jahrhunderte vor Christus von indischen und griechischen Philosophieschulen entwickelt. Etwa 450 v. Chr. pragte Demokrit den Begriff ´atomos, das “Unzerschneidbare”, fur die diskreten Grundbausteine der Materie. Doch erst in der jungeren Vergangenheit konnte dieses philosophische Konzept auch experimentell uberpruft werden.
Experiment as Theseus’s Ship: Which Experiments Preserve Diachronic Identity?
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