José Salt Cairols

Search for lepton flavour number violating Z°-decays

A search for lepton flavour number violating Z0 decays in the channels Z0 → μτ, Z0 → eτ, Z0 → eμ, using the DELPHI detector with data collected during the 1991–94 LEP runs, is described. No signal was found. Upper limits at 95% confidence level for the respective branching fractions of 1.2 × 10−5, 2.2 × 10−5, and 0.25 × 10−5, were obtained.

Emergent algorithms for replica location and selection in data grid

Grid infrastructures for e-Science projects are growing in magnitude terms. Improvements in data Grid replication algorithms may be critical in many of these infrastructures. This paper shows a decentralized replica optimization service, providing a general Emergent Artificial Intelligence (EAI) algorithm for the problem definition. Our aim is to set up a theoretical framework for emergent heuristics in Grid environments. Further, we describe two EAI approaches, the Particle Swarm Optimization PSO-Grid Multiswarm Federation and the Ant Colony Optimization ACO-Grid Asynchronous Colonies Optimization replica optimization algorithms, with some examples. We also present extended results with best performance and scalability features for PSO-Grid Multiswarm Federation.

The GRID Computing Face with the Start of the LHC Experiments

The biggest particle accelerator in the world, the LHC, began to work in August 2008 and the four high energy experiments (ALICE, ATLAS, CMS and LHCb) hosted in the beam crossing caverns start to take data. The amount of collected data was very huge ( about several PB) and the grid infrastructure developed and deployed in the last 9 years was monitored and put under challenging situations. In this talk a review of the main parts of the LCG, the LHC computing grid project, was explained and the recent performance studies obtained at CERN was presented. A special description of the ATLAS computing model was given.

The ATLAS EventIndex: an event Catalogue for Experiments Collecting Large Amounts of Data

Modern scientific experiments collect vast amounts of data that must be catalogued to meet multiple use cases and search criteria. In particular, high-energy physics experiments currently in operation produce several billion events per year. A database with the references to the files including each event in every stage of processing is necessary in order to retrieve the selected events from data storage systems. The ATLAS EventIndex project is studying the best way to store the necessary information using modern data storage technologies (Hadoop, HBase etc.) that allow saving in memory key-value pairs and select the best tools to support this application from the point of view of performance, robustness and ease of use. This paper describes the initial design and performance tests and the project evolution towards deployment and operation during 2014.

Measurement of the Lambda_b lifetime and mass in the ATLAS experiment

Aad, G.; et al., [Unknown]; Aben, R.; Beemster, L.J.; Bentvelsen, S.; Berglund, E.; Bobbink, G.J.; Bos, K.; Boterenbrood, H.; Colijn, A.P.; de Jong, P.; de Nooij, L.; Deluca, C.; Deviveiros, P.O.; Doxiadis, A.D.; Ferrari, P.; Garitaonandia, H.; Geerts, D.A.A.; Gosselink, M.; Hartjes, F.; Hessey, N.P.; Igonkina, O.; Kayl, M.S.; Klous, S.; Kluit, P.; Koffeman, E.; Lee, H.; Lenz, T.; Linde, F.; Luijckx, G.; Massaro, G.; Mechnich, J.; Mussche, I.; Ottersbach, J.P.; Pani, P.; Rijpstra, M.; Ruckstuhl, N.; Ta, D.; Tsiakiris, M.; Turlay, E.; van der Deijl, P.C.; van der Geer, R.; van der Graaf, H.; van der Leeuw, R.; van der Poel, E.; van Vulpen, I.; Verkerke, W.; Vermeulen, J.C.; Vranjes Milosavljevic, M.; Vreeswijk, M.A measurement of the Λb lifetime and mass in the decay channel Λ 0 b → J/ψ(μ+μ−)Λ0(pπ−) is presented. The analysis uses a signal sample of about 2200 Λb and Λ̄ 0 b decays that are reconstructed in 4.9 fb −1 of ATLAS pp collision data collected in 2011 at the LHC center-of-mass energy of 7 TeV. A simultaneous mass and decay time maximum likelihood fit is used to extract the Λb lifetime and mass. They are measured to be τΛb = 1.449± 0.036(stat)± 0.017(syst) ps and mΛb = 5619.7± 0.7(stat)± 1.1(syst) MeV. ar X iv :1 20 7. 22 84 v3 [ he pex ] 2 0 A pr 2 01 3 Measurement of the Λ0b lifetime and mass in the ATLAS experiment The ATLAS Collaboration (Dated: May 2, 2014) A measurement of the Λb lifetime and mass in the decay channel Λ 0 b → J/ψ(μ+μ−)Λ0(pπ−) is presented. The analysis uses a signal sample of about 2200 Λb and Λ̄ 0 b decays that are reconstructed in 4.9 fb−1 of ATLAS pp collision data collected in 2011 at the LHC center-of-mass energy of 7 TeV. A simultaneous mass and decay time maximum likelihood fit is used to extract the Λb lifetime and mass. They are measured to be τΛb = 1.449± 0.036(stat)± 0.017(syst) ps and mΛb = 5619.7± 0.7(stat)± 1.1(syst) MeV.

Measurement of the top quark mass with the template method in the t anti t→lepton+jets channel using ATLAS data

The top quark mass has been measured using the template method in the tt̄→ lepton+jets channel based on data recorded in 2011 with the ATLAS detector at the LHC. The data were taken at a protonproton centre-of-mass energy of √ s = 7 TeV and correspond to an integrated luminosity of 1.04 fb−1. The analyses in the e+jets and μ+jets decay channels yield consistent results. The top quark mass is measured to be mtop = 174.5 ± 0.6stat ± 2.3syst GeV. ar X iv :1 20 3. 57 55 v2 [ he pex ] 1 2 Ju n 20 12 Eur. Phys. J. C manuscript No. (will be inserted by the editor) Measurement of the Top Quark Mass with the Template Method in the tt̄ → lepton+jets Channel using ATLAS Data The ATLAS Collaboration Received: date / Accepted: date Abstract The top quark mass has been measured using the template method in the tt̄→ lepton+jets chan-The top quark mass has been measured using the template method in the tt̄→ lepton+jets channel based on data recorded in 2011 with the ATLAS detector at the LHC. The data were taken at a protonproton centre-of-mass energy of √ s = 7 TeV and correspond to an integrated luminosity of 1.04 fb−1. The analyses in the e+jets and μ+jets decay channels yield consistent results. The top quark mass is measured to be mtop = 174.5 ± 0.6stat ± 2.3syst GeV.The top quark mass has been measured using the template method in the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}

Measurement of t anti t production with a veto on additional central jet activity in pp collisions at √(s)=7 TeV using the ATLAS detector

t\bar{t}\to\mathrm{lepton}+\mathrm{jets}

A search for t[bar over t] resonances in lepton+jets events with highly boosted top quarks collected in pp collisions at √s = 7 TeV with the ATLAS detector

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Observation of a Centrality‐Dependent Dijet Asymmetry in Lead‐Lead Collisions at √SNN= 2.76 TeV with the ATLAS Detector at LHC

\sqrt{s}=7\ \mbox{TeV}

Measurement of the W‐>lnu and Z/gamma*‐>ll production cross sections in protonproton collisions at √s = 7 TeV with the ATLAS detector

\end{document} and correspond to an integrated luminosity of 1.04 fb−1. The analyses in the e+jets and μ+jets decay channels yield consistent results. The top quark mass is measured to be mtop=174.5±0.6stat±2.3syst GeV.