Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 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 sqrt(s) = 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 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-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 chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. 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 bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Measurement of the cross-section for b-jets produced in association with a Z boson at root s=7 TeV with the ATLAS detector ATLAS Collaboration

A measurement is presented of the inclusive cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of root s = 7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb(-1). The event selection requires a Z boson decaying into high P-T electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum p(T) > 25 GeV and rapidity vertical bar y vertical bar < 2.1. After subtraction of background processes, the yield is extracted from the vertex mass distribution of the candidate b-jets. The ratio of this cross-section to the inclusive Z cross-section (the average number of b-jets per Z event) is also measured. Both results are found to be in good agreement with perturbative QCD predictions at next-to-leading order

Operation and performance of the ATLAS Tile Calorimeter in Run 1

The Tile Calorimeter is the hadron calorimeter covering the central region of the ATLAS experiment at the Large Hadron Collider. Approximately 10,000 photomultipliers collect light from scintillating tiles acting as the active material sandwiched between slabs of steel absorber. This paper gives an overview of the calorimeter’s performance during the years 2008–2012 using cosmic-ray muon events and proton–proton collision data at centre-of-mass energies of 7 and 8TeV with a total integrated luminosity of nearly 30 fb−1. The signal reconstruction methods, calibration systems as well as the detector operation status are presented. The energy and time calibration methods performed excellently, resulting in good stability of the calorimeter response under varying conditions during the LHC Run 1. Finally, the Tile Calorimeter response to isolated muons and hadrons as well as to jets from proton–proton collisions is presented. The results demonstrate excellent performance in accord with specifications mentioned in the Technical Design Report

Measurement of charged-particle event shape variables in inclusive root(s)=7 TeV proton-proton interactions with the ATLAS detector

The measurement of charged-particle event shape variables is presented in inclusive inelastic pp collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the LHC. The observables studied are the transverse thrust, thrust minor, and transverse sphericity, each defined using the final-state charged particles' momentum components perpendicular to the beam direction. Events with at least six charged particles are selected by a minimum-bias trigger. In addition to the differential distributions, the evolution of each event shape variable as a function of the leading charged-particle transverse momentum, charged-particle multiplicity, and summed transverse momentum is presented. Predictions from several Monte Carlo models show significant deviations from data

KC 4.1: Rural heritage and urban-rural linkages in the ICOMOS SDGs Policy Guidance

This Knowledge Café aims to provide a discussion platform to contribute to the drafting of a new ICOMOS SDGs Policy Guidance, from the perspective of rural heritage, landscapes and rural-urban linkages. While 50%-plus of global populations are urban dwellers, we tend to forget that the other half dwell in rural places. One of the 7 Priority Actions of the ICOMOS SDGs Working Group in 2018 is the preparation of a consolidated policy statement, as an effective tool for advocacy and communication to wider society and the development world. Based on the need to boost the role of cultural heritage in sustainable development processes, this would be a robust Policy Guidance document, serving to improve the recognition of the role of cultural heritage protection, particularly as defined by SDG 11.4 and the New Urban Agenda. The ICOMOS SDGs Working Group aims to launch this document at the 10th World Urban Forum in 2020 and at the High-Level Political Forum in 2021. The new Policy Guidance aims to emphasize “heritage as a resource, a strategic opportunity”, using the framework of the 3 dimensions of sustainability, economic, social, environmental, and propose adding the 4th dimension of ‘culture’ through an appropriate approach. The document should be based on solid scientific expertise sourced from ICOMOS membership. The Symposium on Rural Heritage: Landscapes and Beyond is a prime opportunity to involve some of this membership, ensuring a diverse and inclusive range of expertise in heritage informs the Policy Guidance. Rural heritage and landscapes, including rural-urban linkages, have great relevance for the intersection of cultural heritage and sustainable development, touching on many SDGs and issues raised in the New Urban Agenda, not to mention the Historic Urban Landscape Recommendation. To cite some examples of this inter-connectedness, the “inter-related categories of continuity and change” addressed during the Symposium, provide the following links: - under ‘Rural Culture’ to SDG 11.4 (change management for tangible rural heritage), SDG 1.5, 2.4, 11.5, 11.b, 13.1 (risk of loss of intangible rural traditions/ practices), SDG 8.9, SDG 12.b (rural cultural tourism), SDG 16.7, 16.a, 17.9, 17.15, 17.17 (identity of people and places); - under ‘Rural economics’ to SDG 1 (poverty eradication), SDG2 (food security), SDG3 (rural agricultural heritage), SDG 8 (improvement of markets and opportunities for rural traditional tools, techniques and rural heritage tourism), SDG 8 (infrastructure, services to small enterprises), SDG 11 (spatial form, territorial policies); - under ‘Rural Environment’ to SDG 6 (water), 13 and 15 (desertification, climate-induced severe weather events, biodiversity, forest management); and - under ‘Rural Society’ to SDG 1 (poverty alleviation) SDG 2 (agriculture), SDG 3.8, 3.c (health services), SDG 16, 17 (bottom-up governance). - Some case studies from ‘Moroccan Rural Heritage’ can be proposed during the session from participants who may have relevant knowledge, to demonstrate these links. The Knowledge Café will feature two speakers, Ege Yildirim and Patricia O’Donnell, giving the conceptual framework of the session, followed by Ilaria Rosetti presenting the method of open discussion, whereby breakout groups (e.g. 3-4 groups of 5-6) can discuss the links of rural heritage issues to the various 17 Goals and Targets under them, concluding with short reporting from each group, to be compiled and disseminated later by the conveners

Study of the response of the ATLAS central calorimeter to pions of energies from 3 to 9GeV

A fully instrumented slice of the ATLAS central detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. in this paper, the response of the central calorimeters to pions with energies in the range between 3 and 9 GeV is presented. The linearity and the resolution of the combined calorimetry (electromagnetic and hadronic calorimeters) was measured and compared to the prediction of a detector simulation program using the toolkit Geant 4. (C) 2009 Elsevier B.V. All rights reserved

Study of the response of the ATLAS central calorimeter to pions of energies from 3 to 9 GeV

A fully instrumented slice of the ATLAS central detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the response of the central calorimeters to pions with energies in the range between 3 and 9 GeV is presented. The linearity and the resolution of the combined calorimetry (electromagnetic and hadronic calorimeters) was measured and compared to the prediction of a detector simulation program using the toolkit Geant 4

Search for the supersymmetric partner of the top quark in p(p)over-bar collisions at root s=1.8 TeV

We report on a search for the supersymmetric partner of the top quark (top squark) produced in t (t) over bar events using 110 ph(-1) of p (p) over bar collisions at roots = 1.8 TeV recorded with the Collider Detector at Fermilab. In the case of a light top squark, the decay of-the top quark into a top squark plus the lightest supersymmetric particle (LSP) could have a significant branching ratio. The observed events are consistent with standard model t (t) over bar production and decay. Hence, we set limits on the branching ratio of the top quark decaying into a top squark plus LSP, excluding branching ratios above 45% for a LSP mass up to 30 GeV/c(2)