1,825 research outputs found

    Recuerdos sobre el comienzo de una gran aventura

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    Discurso del Prof. Dr. Ismael Sánchez Bella, vicerrector de la Universidad de Navarra.

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    At the beginnings of the funerary Megalithism in Iberia at Campo de Hockey necropolis

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    The excavations undertaken at the Campo de Hockey site in 2008 led to the identification of a major Neolithic necropolis in the former Island of San Fernando (Bay of Cádiz). This work presents the results of the latest studies, which indicate that the site stands as one of the oldest megalithic necropolises in the Iberian Peninsula. The main aim of this work is to present with precision the chronology of this necropolis through a Bayesian statistical model that confirms that the necropolis was in use from c. 4300 to 3800 cal BC. The presence of prestige grave goods in the earliest and most monumental graves suggest that the Megalithism phenomenon emerged in relation to maritime routes linked to the distribution of exotic products. We also aim to examine funerary practices in these early megalithic communities, and especially their way of life and the social reproduction system. As such, in addition to the chronological information and the Bayesian statistics, we provide the results of a comprehensive interdisciplinary study, including anthropological, archaeometric and genetic data.Archaeological background: the Campo de Hockey settlement Methods - Tomb typology - Radiocarbon dates and Bayesian analysis. - Bioarchaeology. - DNA - Grave goods Results - Tomb typology - Radiocarbon dating: Bayesian analysis - Bioarchaeology. - DNA - Grave goods. Discussion and conclusions

    Natural and anthropogenic processes in La Janda basin (SW Iberia) from the Late Pleistocene to the Mid-Late Holocene

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    A multiproxy study (pollen, non-pollen palynomorphs, sedimentology, and geochemistry) was carried out in two cores drilled in La Janda basin (SW Iberia) to trace the environmental evolution and human impact on the landscape. An incised fluvial valley existed in the basin during the Late Pleistocene, followed by a transitional environment characterized by the development of saltmarsh vegetation affected by the increased marine influence ca. 10/8.7 ka cal BP. During this period comprising the Upper Palaeolithic and Mesolithic (>∼7.8 ka cal BP), the impact of hunter-gatherer groups on the landscape was rather low according to palynological and geochemical records. A restricted estuary connected to the sea was identified in La Janda between ca. 10/8.7-3.5/3.3 ka cal BP, coinciding with a predominance of saltmarsh vegetation developing on saline shore soils and the punctual presence of foraminifera and dynoflagellate cysts. The anthropogenic pressure was progressively increasing during the Neolithic, especially from ca. 7 ka cal BP, with markers suggesting herding/livestock activities prior to the punctual presence of cereals, which is only confirmed by the archaeological record ca. 6 ka cal BP. Human pressure become more noticeable throughout the Chalcolithic and Bronze Age (∼5-3 ka cal BP), period during which a new transitional phase is recorded in La Janda (ca. 3.5/3.3-1.3 ka cal BP), culminating in the terrestrialization of the area. The predominance of freshwater taxa and decrease of saltmarsh vegetation is observed during this period, and the transformation of the landscape for agricultural activities over the last centuries is reflected in the local presence of cereals and markers of erosive processes.This research was funded by the Deutsche Forschungsgemeinschaft-DFG (project no.57444011 – SFB 806); a “Severo Ochoa” extraordinary grant for excellence IGME, CSIC (AECEX2021); the Consejería de Cultura of the Junta de Andalucía (projects DGBC/IDBC3741 and 4766); the FEDER/MINECO-AGEINVES (HAR2017-8734P); and the Operational Programme and Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia (FEDERUCA18-106917)Peer reviewe

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Measurement of the flavour composition of dijet events in pp collisions at root s=7 TeV with the ATLAS detector

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    This paper describes a measurement of the flavour composition of dijet events produced in pp collisions at √s=7 TeV using the ATLAS detector. The measurement uses the full 2010 data sample, corresponding to an integrated luminosity of 39 pb−1. Six possible combinations of light, charm and bottom jets are identified in the dijet events, where the jet flavour is defined by the presence of bottom, charm or solely light flavour hadrons in the jet. Kinematic variables, based on the properties of displaced decay vertices and optimised for jet flavour identification, are used in a multidimensional template fit to measure the fractions of these dijet flavour states as functions of the leading jet transverse momentum in the range 40 GeV to 500 GeV and jet rapidity |y|<2.1. The fit results agree with the predictions of leading- and next-to-leading-order calculations, with the exception of the dijet fraction composed of bottom and light flavour jets, which is underestimated by all models at large transverse jet momenta. The ability to identify jets containing two b-hadrons, originating from e.g. gluon splitting, is demonstrated. The difference between bottom jet production rates in leading and subleading jets is consistent with the next-to-leading-order predictions

    Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

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    The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for dark matter in events with heavy quarks and missing transverse momentum in pp collisions with the ATLAS detector

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    This article reports on a search for dark matterpair production in association with bottom or top quarks in20.3fb−1ofppcollisions collected at√s=8TeVbytheATLAS detector at the LHC. Events with large missing trans-verse momentum are selected when produced in associationwith high-momentum jets of which one or more are identifiedas jets containingb-quarks. Final states with top quarks areselected by requiring a high jet multiplicity and in some casesa single lepton. The data are found to be consistent with theStandard Model expectations and limits are set on the massscale of effective field theories that describe scalar and tensorinteractions between dark matter and Standard Model par-ticles. Limits on the dark-matter–nucleon cross-section forspin-independent and spin-dependent interactions are alsoprovided. These limits are particularly strong for low-massdark matter. Using a simplified model, constraints are set onthe mass of dark matter and of a coloured mediator suitableto explain a possible signal of annihilating dark matter
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