35 research outputs found

    Measurement of vector boson production cross sections and their ratios using pp collisions at s=13.6 TeV with the ATLAS detector

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    Beam-induced backgrounds measured in the ATLAS detector during local gas injection into the LHC beam vacuum

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    Measurement of vector boson production cross sections and their ratios using pp collisions at √s = 13.6 TeV with the ATLAS detector

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    Abstract available from publisher's website

    Beam-induced backgrounds measured in the ATLAS detector during local gas injection into the LHC beam vacuum

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    Inelastic beam-gas collisions at the Large Hadron Collider (LHC), within a few hundred metres of the ATLAS experiment, are known to give the dominant contribution to beam backgrounds. These are monitored by ATLAS with a dedicated Beam Conditions Monitor (BCM) and with the rate of fake jets in the calorimeters. These two methods are complementary since the BCM probes backgrounds just around the beam pipe while fake jets are observed at radii of up to several metres. In order to quantify the correlation between the residual gas density in the LHC beam vacuum and the experimental backgrounds recorded by ATLAS, several dedicated tests were performed during LHC Run 2. Local pressure bumps, with a gas density several orders of magnitude higher than during normal operation, were introduced at different locations. The changes of beam-related backgrounds, seen in ATLAS, are correlated with the local pressure variation. In addition the rates of beam-gas events are estimated from the pressure measurements and pressure bump profiles obtained from calculations. Using these rates, the efficiency of the ATLAS beam background monitors to detect beam-gas events is derived as a function of distance from the interaction point. These efficiencies and characteristic distributions of fake jets from the beam backgrounds are found to be in good agreement with results of beam-gas simulations performed with theFluka Monte Carlo programme

    Search for heavy Majorana neutrinos in e±e± and e±μ± final states via WW scattering in pp collisions at √s = 13 TeV with the ATLAS detector

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    A search for heavy Majorana neutrinos in scattering of same-sign W boson pairs in proton–proton collisions at √s = 13 TeV at the LHC is reported. The dataset used corresponds to an integrated luminosity of 140 fb−1, collected with the ATLAS detector during 2015–2018. The search is performed in final states including a same-sign ee or eμ pair and at least two jets with large invariant mass and a large rapidity difference. No significant excess of events with respect to the Standard Model background predictions is observed. The results are interpreted in a benchmark scenario of the Phenomenological Type-I Seesaw model. New constraints are set on the values of the |VeN|2 and |VeN V*μN| parameters for heavy Majorana neutrino masses between 50 GeV and 20 TeV, where VℓN is the matrix element describing the mixing of the heavy Majorana neutrino mass eigenstate with the Standard Model neutrino of flavour ℓ = e, μ. The sensitivity to the Weinberg operator is investigated and constraints on the effective ee and eμ Majorana neutrino masses are reported. The statistical combination of the ee and eμ channels with the previously published μμ channel is performed

    Measurements of electroweak W±Z boson pair production in association with two jets in pp collisions at √s = 13 TeV with the ATLAS detector

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    Measurements of integrated and differential cross-sections for electroweak W±Z production in association with two jets (W±Zjj) in proton-proton collisions are presented. The data collected by the ATLAS detector at the Large Hadron Collider from 2015 to 2018 at a centre-of-mass energy of √ s = 13 TeV are used, corresponding to an integrated luminosity of 140 fb−1 . The W±Zjj candidate events are reconstructed using leptonic decay modes of the gauge bosons. Events containing three identified leptons, either electrons or muons, and two jets are selected. Processes involving pure electroweak W±Zjj production at Born level are separated from W±Zjj production involving a strong coupling. The measured integrated fiducial cross-section of electroweak W±Zjj production per lepton flavour is σW Zjj−EW→ℓ ′ νℓℓjj = 0.368 ± 0.037 (stat.) ± 0.059 (syst.) ± 0.003 (lumi.) fb, where ℓ and ℓ ′ are either an electron or a muon. Respective cross-sections of electroweak and strong W±Zjj production are measured separately for events with exactly two jets or with more than two jets, and in three bins of the invariant mass of the two jets. The inclusive W±Zjj production cross-section, without separating electroweak and strong production, is also measured to be σW Zjj→ℓ ′ νℓℓjj = 1.462 ± 0.063 (stat.) ± 0.118 (syst.) ± 0.012 (lumi.) fb, per lepton flavour. The inclusive W±Zjj production cross-section is measured differentially for several kinematic observables. Finally, the measurements are used to constrain anomalous quartic gauge couplings by extracting 95% confidence level intervals on dimension-8 operators

    Effects of Strontium Ranelate Administration on Calcium Metabolism in Female Patients with Postmenopausal Osteoporosis and Primary Hyperparathyroidism

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    We investigated possible changes of parameters of calcium metabolism induced by strontium ranelate (SR). Twenty-three patients with postmenopausal osteoporosis (PO) and 14 with primary hyperparathyroidism (PHPT) were studied while taking 2 g/day of SR. Women with PO and 10 healthy age-matched control women were also daily supplemented with 1,000 mg calcium and 800 IU vitamin D. All subjects were studied at baseline and after 7 and 30 days; PO women and controls were also investigated at 180 and 360 days of treatment. Serum ionized calcium (iCa), phosphate (sP), magnesium, creatinine, 25-hydroxycholecalciferol (25[OH]D), 1,25-dihydroxycholecalciferol (1,25[OH](2)D), serum parathyroid hormone (PTH) were measured. In spot urine, we assessed calcium and phosphate over creatinine ratios (uCa/Cr, uP/Cr), calcium excretion (Ca ex) and renal phosphate threshold (TmP/GFR); in 24-h urine, calcium and magnesium over creatinine clearance ratios (CaCl/CrCl and MgCl/CrCl). In PO, SR administration was associated with a significant decrease of PTH and 1,25(OH)(2)D levels but an increase of sP (p < 0.001). SR also significantly increased Ca/Cr, Ca ex, and TmP/GFR in spot urine and CaCl/CrCl in both spot and 24-h urine (p = 0.004 to < 0.001). In PHPT, SR significantly decreased iCa and increased sP, slightly modifying PTH, 25(OH)D, and 1,25(OH)(2)D values. Also in PHPT, Ca ex and CaCl/CrCl of spot and 24-h urine, as TmP/GFR, significantly increased (all p < 0.02). SR influenced the main parameters of calcium homeostasis, probably through the calcium-sensing receptor

    Sex hormones and bone health in males

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    Sex steroids play a key role in maintaining skeletal integrity lifelong, through a complex variety of endocrine, but also paracrine and possibly autocrine actions. The current knowledge that androgens may act as pro-hormones for estrogens has seriously challenged many traditional views, so that, at least for their skeletal actions, these can no longer be considered exclusively "male" or "female" hormones. (C) 2010 Elsevier Inc. All rights reserved

    ACCURACY OF VERTEBRAL FRACTURE ASSESSMENT BY DUAL-ENERGY X-RAY ABSORPTIOMETRY USING GE IDXA COMPARED TO CONVENTIONAL RADIOGRAPHY

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    26 subjects (9.5%) had multiple vertebral fractures detected by SQ Rx technique and 28 subjects (10.2%) by iDXA . Considering radiological SQ assessment as the gold standard, iDXA sensitivity was 87% and the specificity was 96% (Positive Predictive Value 88%; Objective: This prospective investigation was carried out in order to evaluate the accuracy of vertebral fracture assessment by dual-energy X-ray absorptiometry using GE iDXA device (GE Medical Systems Lunar, Madison, WI, USA) compared to conventional radiography.Subjects and Methods: We enrolled 273 subjects (207 females and 68 males, age range 28-85 years) consecutively studied at our Mineral Metabolism Centre, which were undergoing a spine vertebral X-ray evaluation. Lateral images of the spine, from T4 to L4, by both conventional X-ray and iDXA device, were acquired in each subject on the same day, after informed consent was obtained. The radiographs were evaluated by an experienced skeletal radiologist (D.D.), using the semiquantitative (SQ) method. The iDXA images were evaluated by a trained operator using a specific software (enCORE).Results: By means of SQ radiological technique, we evaluated 3515 (99%) of the 3549 available vertebrae, and identified 151 vertebral deformities (101 mild and 50 moderate or severe). By means of iDXA we visualized 3405 (96%) vertebrae and identified 150 vertebral deformities (100 mild and 50 moderate or severe). Ninety-two subjects (33.7% of the total sample) were identified as having vertebral fractures by SQ Rx technique and eighty-seven subjects (31.9%) fractured were recognized by iDXA (χ2 = n.s.). A single fracture was detected in 66 patients (24.2%) by conventional radiographs and in 59 subjects (21.6%) by iDXA; Negative Predictive Value 97%). Agreement between radiographs and iDXA was 96% with a kappa statistic of 0.91 (confidence interval 0.82-0.96).Conclusions: According to the results obtained, iDXA and SQ radiological technique demonstrated good agreement in classifying vertebrae as normal or deformed. Therefore, since iDXA performs spine images with good resolution and lower dose, it proves to be useful in the clinical evaluation of patients at risk of osteoporosis or for the selection of patients for osteoporosis-related clinical trials

    The Italian Observational Study on Severe Osteoporosis (ISSO): 24-month results on incidence of fractures and adherence to treatment

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    To estimate the proportion of patients with very severe osteoporosis (those covered by the reimbursement criteria of the Italian National Health Service) experiencing new vertebral and non-vertebral fragility fractures in the first 24 months of a new anti-osteoporosis treatment
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