226 research outputs found

    Ulrich Beck: modernità e cosmopolitismo fra Occidente e non-Occidente

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    Questo contributo offre alcune considerazioni su due dei temi centrali della riflessione di Ulrich Beck: la (ri)formulazione dell'idea di modernità nei termini di "seconda modernità"; e la conseguente esigenza di formulazione di un adeguato corredo metodologico e concettuale di impronta cosmopolita per l'analisi di questa nuova condizione della storia dell'umanità. L'idea di una "seconda modernità", proiettata al di là dei caratteri industriali e delle categorie interpretative della modernità classica, nell'offrire un'alternativa alla tesi dell'avvento di una condizione postmoderna, ne coopta e neutralizza la critica, facendo uso dell'incertezza epistemologica prodotta dalla crisi dei fondamenti scientifici moderni per sancire teoricamente e legittimare un'incertezza sociale a sua volta deterministicamente ricondotta all'avvento di una società – anche globale – del rischio. La proposta di un cosmopolitismo metodologico come necessario per l'analisi della seconda modernità elude la questione relativa all'inadeguatezza di categorie analitiche metodologicamente nazionaliste per lo studio della prima modernità; e, al tempo stesso, marginalizza o silenzia, eurocentricamente, tanto il ruolo costitutivo del mondo non occidentale nella genealogia intellettuale e istituzionale della modernità, quanto il "lato oscuro" di quest'ultima così come definita dall'Occidente

    PGO models in the envelope function and effective mass approximations

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    A recipe to design quantum devices that exhibit the theoretical pseudo-Gaussian oscillator electronic states properties is given. The algorithm is described en detail and is illustrated by the computation of a Mn x Cd 1- x Te ternary alloy pseudo-Gaussian heterostructure. The numerical procedure reaches beyond of pseudo-Gaussian models and can be used for designing epitaxial growth devices with desired electronic states structure. The calculations are carried out in the envelope function and effective mass approximations. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2011

    Search for Heavy Neutral Leptons in Decays of W Bosons Using a Dilepton Displaced Vertex in p s=13 TeV pp Collisions with the ATLAS Detector

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    A search for a long-lived, heavy neutral lepton ( N ) in 139 fb - 1 of s = 13 TeV p p collision data collected by the ATLAS detector at the Large Hadron Collider is reported. The N is produced via W → N μ or W → N e and decays into two charged leptons and a neutrino, forming a displaced vertex. The N mass is used to discriminate between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the N with the left-handed neutrino states for the N mass range 3 GeV < m N < 15 GeV . For the first time, limits are given for both single-flavor and multiflavor mixing scenarios motivated by neutrino flavor oscillation results for both the normal and inverted neutrino-mass hierarchies

    Strong constraints on jet quenching in centrality-dependent pp+Pb collisions at 5.02 TeV from ATLAS

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    Jet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including pppp and pp+Pb collisions. In contrast, while jet quenching is observed in Pb+Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36 nb1^{-1} of pp+Pb and 3.6 pb1^{-1} of pppp collisions at 5.02 TeV. The yields of charged hadrons with pTch>0.5p_\mathrm{T}^\mathrm{ch} >0.5 GeV near and opposite in azimuth to jets with pTjet>30p_\mathrm{T}^\mathrm{jet} > 30 or 60 GeV, and the ratios of these yields between pp+Pb and pppp collisions, IpPbI_{p\mathrm{Pb}}, are reported. The collision centrality of pp+Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The IpPbI_{p\mathrm{Pb}} values are consistent with unity within a few percent for hadrons with pTch>4p_\mathrm{T}^\mathrm{ch} >4 GeV at all centralities. These data provide new, strong constraints which preclude almost any parton energy loss in central pp+Pb collisions

    Strong Constraints on Jet Quenching in Centrality-Dependent p plus Pb Collisions at 5.02 TeV from ATLAS

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    Jet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including p p and p + Pb collisions. In contrast, while jet quenching is observed in Pb + Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36 nb - 1 of p + Pb and 3.6 pb - 1 of p p collisions at 5.02 TeV. The yields of charged hadrons with p T ch > 0.5 GeV near and opposite in azimuth to jets with p T jet > 30 or 60 GeV, and the ratios of these yields between p + Pb and p p collisions, I p Pb , are reported. The collision centrality of p + Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The I p Pb values are consistent with unity within a few percent for hadrons with p T ch > 4 GeV at all centralities. These data provide new, strong constraints that preclude almost any parton energy loss in central p + Pb collisions

    Search for a new pseudoscalar decaying into a pair of muons in events with a top-quark pair at √s = 13 TeV with the ATLAS detector

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    A search for a new pseudoscalar a -boson produced in events with a top-quark pair, where the a -boson decays into a pair of muons, is performed using √ s = 13     TeV p p collision data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139     fb − 1 . The search targets the final state where only one top quark decays to an electron or muon, resulting in a signature with three leptons e μ μ and μ μ μ . No significant excess of events above the Standard Model expectation is observed and upper limits are set on two signal models: p p → t ¯ t a and p p → t ¯ t with t → H ± b , H ± → W ± a , where a → μ μ , in the mass ranges 15     GeV < m a < 72     GeV and 120     GeV ≤ m H ± ≤ 160     GeV

    Measurement of the centrality dependence of the dijet yield in p+Pb collisions at √sNN = 8.16 TeV with the ATLAS detector

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    ATLAS measured the centrality dependence of the dijet yield using 165     nb − 1 of p + Pb data collected at √ s NN = 8.16     TeV in 2016. The event centrality, which reflects the p + Pb impact parameter, is characterized by the total transverse energy registered in the Pb-going side of the forward calorimeter. The central-to-peripheral ratio of the scaled dijet yields, R CP , is evaluated, and the results are presented as a function of variables that reflect the kinematics of the initial hard parton scattering process. The R CP shows a scaling with the Bjorken x of the parton originating from the proton, x p , while no such trend is observed as a function of x Pb . This analysis provides unique input to understanding the role of small proton spatial configurations in p + Pb collisions by covering parton momentum fractions from the valence region down to x p ∼ 10 − 3 and x Pb ∼ 4 × 10 − 4

    Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery

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    Search for events with a pair of displaced vertices from long-lived neutral particles decaying into hadronic jets in the ATLAS muon spectrometer in pp collisions at √s = 13 TeV

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    A search for events with two displaced vertices from long-lived particle (LLP) pairs using data collected by the ATLAS detector at the LHC is presented. This analysis uses 139     fb − 1 of proton-proton collision data at √ s = 13     TeV recorded in 2015–2018. The search employs techniques for reconstructing vertices of LLPs decaying to jets in the muon spectrometer displaced between 3 and 14 m with respect to the primary interaction vertex. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined. For the Higgs boson with a mass of 125 GeV, the paper reports the first exclusion limits for branching fractions into neutral long-lived particles below 0.1%, while branching fractions above 10% are excluded at 95% confidence level for LLP proper lifetimes ranging from 4 cm to 72.4 m. In addition, the paper present the first results for the decay of LLPs into t ¯ t in the ATLAS muon spectrometer
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