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 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

Compound effect of EHD and surface roughness in pool boiling and CHF with R-123

This article is a post-print version of the fianl published article which may be accessed at the link below.Saturated pool boiling of R-123 at 1 bar, including the critical heat flux (CHF), was enhanced by modifying the surface characteristics and applying a high intensity electrostatic field, the latter termed electrohydrodynamic (and abbreviated EHD) enhancement. The heat flux was varied from very low values in the natural convection regime up to CHF. Experiments were performed with increasing and decreasing heat flux to study boiling hysteresis without and with EHD. Boiling occurred on the sand blasted surface of a cylindrical copper block with embedded electrical heating elements, with standardized surface parameter Pa = 3.5 μm. The electric field was generated by a potential of 5 kV to 25 kV, applied through a 40 mm diameter circular electrode of ss-304 wire mesh, aperture size 5.1 mm, located at distances of 5 - 60 mm from the surface, with most of the data obtained for 20 mm. The data for the rough surface were compared with earlier data for a smooth surface and indicated a significant increase in the heat transfer rates. EHD produced a further increase in the heat transfer rates, particularly at low heat flux values and near the CHF. Boiling hysteresis was reduced progressively by EHD and eliminated at high field strength.This work was supported by Government of Pakistan under a scholarship programme

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

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN

Search for diphoton events with large missing transverse momentum in 1 fb^-1 of 7 TeV proton–proton collision data with the ATLAS detector

A search for diphoton events with large missing transverse momentum has been performed using 1.07 fb−1of proton–proton collision data at &#8730;s=7  TeV recorded with the ATLAS detector. No excess of events was observed above the Standard Model prediction and 95% Confidence Level (CL) upper limits are set on the production cross section for new physics. The limits depend on each model parameter space and vary as follows: &#963;&#60;(22–129) fb in the context of a generalised model of gauge-mediated supersymmetry breaking (GGM) with a bino-like lightest neutralino, &#963;&#60;(27–91) fb in the context of a minimal model of gauge-mediated supersymmetry breaking (SPS8), and &#963;&#60; (15–27) fb in the context of a specific model with one universal extra dimension (UED). A 95% CL lower limit of 805 GeV, for bino masses above 50 GeV, is set on the GGM gluino mass. Lower limits of 145 TeV and 1.23 TeV are set on the SPS8 breaking scale &#8743; and on the UED compactification scale 1/R, respectively. These limits provide the most stringent tests of these models to date

Searches for supersymmetry with the ATLAS detector using final states with two leptons and missing transverse momentum in root s=7 TeV proton-proton collisions

Results of three searches are presented for the production of supersymmetric particles decaying into final states with missing transverse momentum and exactly two isolated leptons, e or mu. The analysis uses a data sample collected during the first half of 2011 that corresponds to a total integrated luminosity of 1 fb(-1) of root s = 7 TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. Opposite-sign and same-sign dilepton events are separately studied, with no deviations from the Standard Model expectation observed. Additionally, in opposite-sign events, a search is made for an excess of same-flavour over different-flavour lepton pairs. Effective production cross sections in excess of 9.9 fb for opposite-sign events containing supersymmetric particles with missing transverse momentum greater than 250 GeV are excluded at 95% CL For same-sign events containing supersymmetric particles with missing transverse momentum greater than 100 GeV, effective production cross sections in excess of 14.8 fb are excluded at 95% CL The latter limit is interpreted in a simplified electroweak gaugino production model excluding chargino masses up to 200 GeV, under the assumption that slepton decay is dominant. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved

Search for the Standard Model Higgs boson in the decay channel H→ZZ(*)→4ℓ with the ATLAS detector

A search for the Standard Model Higgs boson in the decay channel H -> ZZ(()*()) l(+)l(-)l'l'(-), where l = e, mu, is presented. Proton-proton collision data at root s = 7 TeV recorded with the ATLAS detector and corresponding to an average integrated luminosity of 2.1 fb(-1) are compared to the Standard Model expectations. Upper limits on the production cross section of a Standard Model Higgs boson with a mass between 110 and 600 GeV are derived. The observed (expected) 95% confidence level upper limit on the production cross section for a Higgs boson with a mass of 194 GeV, the region with the best expected sensitivity for this search, is 0.99 (1.01) times the Standard Model prediction. The Standard Model Higgs boson is excluded at 95% confidence level in the mass ranges 191-197, 199-200 and 214-224 GeV. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved

Search for diphoton events with large missing transverse momentum in 1 fb(-1) of 7 TeV proton-proton collision data with the ATLAS detector ATLAS Collaboration

A search for diphoton events with large missing transverse momentum has been performed using 1.07 fb -1 of proton-proton collision data at s=7 TeV recorded with the ATLAS detector. No excess of events was observed above the Standard Model prediction and 95% Confidence Level (CL) upper limits are set on the production cross section for new physics. The limits depend on each model parameter space and vary as follows: Λ&lt;(22-129) fb in the context of a generalised model of gauge-mediated supersymmetry breaking (GGM) with a bino-like lightest neutralino, σ&lt;(27-91) fb in the context of a minimal model of gauge-mediated supersymmetry breaking (SPS8), and σ&lt;(15-27) fb in the context of a specific model with one universal extra dimension (UED). A 95% CL lower limit of 805 GeV, for bino masses above 50 GeV, is set on the GGM gluino mass. Lower limits of 145 TeV and 1.23 TeV are set on the SPS8 breaking scale Λ and on the UED compactification scale 1/R, respectively. These limits provide the most stringent tests of these models to date. © 2012 CERN