1,004 research outputs found

    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+→Ό+ÎœW^+ \rightarrow \mu^+\nu and W−→Ό−ΜW^- \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 chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

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    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

    Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

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    A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Bacteria in milk from anterior and posterior mammary glands in sows affected and unaffected by postpartum dysgalactia syndrome (PPDS)

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    <p>Abstract</p> <p>Background</p> <p>The performance of piglet weight gain is strongly dependent on the sow's ability to meet the demand for adequate milk. Postparturient disorders, especially those subsumed under the term postpartum dysgalactia syndrome (PPDS), can alter or reduce the milk production sensitively, resulting in starving piglets. The aim of this study was to gather further information about the prevalence of different bacterial species in the anterior and posterior mammary glands of sows with respect to the clinical appearance of PPDS.</p> <p>Methods</p> <p>In this study, the health status of 56 sows after farrowing was determined with special regard to mastitis and dysgalactia. Pooled milk samples from anterior and posterior glands were taken from both affected and non-affected animals and analysed bacteriologically for the presence of a wide spectrum of different pathogens.</p> <p>Results</p> <p>Mainly <it>Escherichia coli</it>, staphylococci and streptococci were detected in high percentages but without significant differences in healthy and diseased animals and anterior and posterior glands. However, the large percentages of coliform bacteria suggested a transmission route via faecal contamination.</p> <p>Conclusion</p> <p>In this study, the prevalence of different bacteria in anterior and posterior glands in PPDS positive and negative sows was analysed. No significant differences in bacteria of healthy and diseased sows were assessed. Therefore, the development of clinical PPDS and actual infection seems to be largely dependant on individual resistance in single sows.</p

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    Đ˜Đ·ŃƒŃ‡Đ”ĐœĐ° ĐżĐŸŃ‚Đ”ĐœŃ†ĐžĐ°Đ»ŃŒĐœĐ°Ń Đ°ĐșтоĐČĐœĐŸŃŃ‚ŃŒ ĐŽĐŸĐœĐœĐŸĐč ĐŒĐžĐșŃ€ĐŸŃ„Đ»ĐŸŃ€Ń‹ ĐČ ĐŒĐ”ŃŃ‚Đ°Ń… ŃƒŃ‚Đ”Ń‡ĐșĐž ĐŸŃŃ‚Đ°Ń‚ĐșĐŸĐČ Ń…ĐžĐŒĐžŃ‡Đ”ŃĐșох Ń‚ĐŸĐșсОĐșĐ°ĐœŃ‚ĐŸĐČ, Đ·Đ°Ń‚ĐŸĐżĐ»Đ”ĐœĐœŃ‹Ń… ĐČ ĐżĐ”Ń€ĐžĐŸĐŽ Đ’Ń‚ĐŸŃ€ĐŸĐč ĐœĐžŃ€ĐŸĐČĐŸĐč ĐČĐŸĐčĐœŃ‹ Đ„Đ„ ĐČ. ĐžŃ‚ĐŒĐ”Ń‡Đ”ĐœŃ‹ ĐŸŃĐŸĐ±Đ”ĐœĐœĐŸŃŃ‚Đž ĐČĐŸŃŃŃ‚Đ°ĐœĐŸĐČĐ»Đ”ĐœĐžŃ Đ¶ĐžĐ·ĐœĐ”ĐŽĐ”ŃŃ‚Đ”Đ»ŃŒĐœĐŸŃŃ‚Đž ĐŒĐžĐșŃ€ĐŸŃ„Đ»ĐŸŃ€Ń‹ про Ń€Đ°Đ·Đ»ĐžŃ‡ĐœŃ‹Ń… ŃƒŃ€ĐŸĐČĐœŃŃ… Đ·Đ°ĐłŃ€ŃĐ·ĐœĐ”ĐœĐžŃ ĐŽĐŸĐœĐœŃ‹Ń… ĐŸŃ‚Đ»ĐŸĐ¶Đ”ĐœĐžĐč ĐŒŃ‹ŃˆŃŒŃĐșĐŸĐŒ Đž Ń…Đ»ĐŸŃ€ĐžŃ€ĐŸĐČĐ°ĐœĐœŃ‹ĐŒĐž ĐŸŃ€ĐłĐ°ĐœĐžŃ‡Đ”ŃĐșĐžĐŒĐž ŃŃƒĐ»ŃŒŃ„ĐžĐŽĐ°ĐŒĐž. ĐŸĐŸĐ»ŃƒŃ‡Đ”ĐœĐœŃ‹Đ” Ń€Đ”Đ·ŃƒĐ»ŃŒŃ‚Đ°Ń‚Ń‹ пДрспДĐșтоĐČĐœĐŸ ĐžŃĐżĐŸĐ»ŃŒĐ·ĐŸĐČать про ĐŸŃ†Đ”ĐœĐșĐ” эĐșĐŸĐ»ĐŸĐłĐžŃ‡Đ”ŃĐșĐŸĐłĐŸ ŃĐŸŃŃ‚ĐŸŃĐœĐžŃ ĐŽĐŸĐœĐœŃ‹Ń… ĐŸŃ‚Đ»ĐŸĐ¶Đ”ĐœĐžĐč ĐČ Đ·Đ°ĐłŃ€ŃĐ·ĐœĐ”ĐœĐœŃ‹Ń… ĐżŃ€ĐžĐ±Ń€Đ”Đ¶ĐœŃ‹Ń… Đ°ĐșĐČĐ°Ń‚ĐŸŃ€ĐžŃŃ…

    Combination of the W boson polarization measurements in top quark decays using ATLAS and CMS data at root s=8 TeV

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    The combination of measurements of the W boson polarization in top quark decays performed by the ATLAS and CMS collaborations is presented. The measurements are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of about 20 fb(-1)for each experiment. The measurements used events containing one lepton and having different jet multiplicities in the final state. The results are quoted as fractions of W bosons with longitudinal (F-0), left-handed (F-L), or right-handed (F-R) polarizations. The resulting combined measurements of the polarization fractions are F-0= 0.693 +/- 0.014 and F-L= 0.315 +/- 0.011. The fractionF(R)is calculated from the unitarity constraint to be F-R=-0.008 +/- 0.007. These results are in agreement with the standard model predictions at next-to-next-to-leading order in perturbative quantum chromodynamics and represent an improvement in precision of 25 (29)% for F-0(F-L) with respect to the most precise single measurement. A limit on anomalous right-handed vector (V-R), and left- and right-handed tensor (g(L), g(R)) tWb couplings is set while fixing all others to their standard model values. The allowed regions are [-0.11,0.16] for V-R, [-0.08,0.05] for g(L), and [-0.04,0.02] for g(R), at 95% confidence level. Limits on the corresponding Wilson coefficients are also derived.Peer reviewe

    Measurement of hadronic event shapes in high-p T multijet final states at √s = 13 TeV with the ATLAS detector

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    A measurement of event-shape variables in proton-proton collisions at large momentum transfer is presented using data collected at s = 13 TeV with the ATLAS detector at the Large Hadron Collider. Six event-shape variables calculated using hadronic jets are studied in inclusive multijet events using data corresponding to an integrated luminosity of 139 fb−1. Measurements are performed in bins of jet multiplicity and in different ranges of the scalar sum of the transverse momenta of the two leading jets, reaching scales beyond 2 TeV. These measurements are compared with predictions from Monte Carlo event generators containing leading-order or next-to-leading order matrix elements matched to parton showers simulated to leading-logarithm accuracy. At low jet multiplicities, shape discrepancies between the measurements and the Monte Carlo predictions are observed. At high jet multiplicities, the shapes are better described but discrepancies in the normalisation are observed. [Figure not available: see fulltext.

    Measurements of top-quark pair differential and double-differential cross-sections in the \u2113 +jets channel with pp collisions at 1as=13 TeV using the ATLAS detector

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    Search for diboson resonances in hadronic final states in 139 fb −1 of pp collisions at s = 13 TeV with the ATLAS detector

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    Abstract: Narrow resonances decaying into W W, W Z or ZZ boson pairs are searched for in 139 fb−1 of proton-proton collision data at a centre-of-mass energy of s = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider from 2015 to 2018. The diboson system is reconstructed using pairs of high transverse momentum, large-radius jets. These jets are built from a combination of calorimeter- and tracker-inputs compatible with the hadronic decay of a boosted W or Z boson, using jet mass and substructure properties. The search is performed for diboson resonances with masses greater than 1.3 TeV. No significant deviations from the background expectations are observed. Exclusion limits at the 95% confidence level are set on the production cross-section times branching ratio into dibosons for resonances in a range of theories beyond the Standard Model, with the highest excluded mass of a new gauge boson at 3.8 TeV in the context of mass-degenerate resonances that couple predominantly to gauge bosons
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