2,025 research outputs found
Measurement of the Differential Production Cross Section of W Bosons and Charge Asymmetry at �s = 7 TeV with the ATLAS Detector
No full textThis document presents a measurement of the production cross section of W
bosons and of its charge asymmetry in proton-proton collisions at a centre of mass energy of 7 TeV with the ATLAS detector. These measurements provide information on the momentum fraction of the protons carried by the partons contributing to the W production and therefore allow to better understand the parton distribution functions of the proton.
The W candidate events are selected in the W�enu decay mode. The LAr electromagnetic calorimeter plays an important role in the detection of electrons and the author has worked on the on-line energy reconstruction in the LAr detectors. A subject which is treated in some detail is the evaluation of the charge misidentification rates for electrons and positrons. This is a key ingredient for charge related measurements such as the W charge asymmetry.
In this document, the W production cross section times the branching ratio is studied inclusively, as a function of the lepton pseudorapidity and as a double differential measurement as a function of the lepton pseudorapidity and transverse energy. The charge asymmetry measurement is presented as a function of the lepton pseudorapidity and as a double differential measurement as well. The data were recorded by the ATLAS detector in 2011 and correspond to 4.7 fb�1
Background and signal estimation for a low mass Higgs boson at the LHC
No full textThe discovery of the Higgs boson(s) is the major goal of the LHC which will start taking data in 2008. In this work a data driven extraction of the background and statistical signal significance in the H→ZZ→4ℓ decay channel is presented. The background for Higgs masses as low as 130 GeV can be extracted with an error of 20%, using a sideband measurement from a single 30 fb-1 experiment. The predicted background distribution is best described by a double asymmetric Gaussian. An analytic formula is introduced which provides an accurate p-value that a Higgs discovery claim is consistent with a background fluctuation. The formula can be used in a single real measurement at LHC using as input the measured background and the profile likelihood asymmetric errors of this measurement. The method presented here can be applied to the general case of extrapolating from a signal-free data region to a candidate signal region. This is the case of supersymmetry searches at the LHC
ATLAS Status, Results and Prospects
No full textThe ATLAS detector status and first results with 900GeV and 7TeV center of mass energy are reviewed
Reversal of rocuronium induced neuromuscular block with sugammadex or neostigmine: a large observational study.
No full textBACKGROUND:
This 'real-life' study aimed to analyze the time from the start of neostigmine or sugammadex administration to recovery to a train of four ratio (TOFr) of 0.9 in a real-life in patients receiving rocuronium. The secondary aims were to assess the proportion of patients: presenting TOFr < 0.9 after 5, 10, and 20 min from reversal agent administration, receiving opioids for intraoperative analgesia and extubated in the post-anesthesia care unit (PACU).
METHODS:
This was a multisite, prospective, nonrandomized, observational real-life study. Reversal agent was administered at either T2 reappearance or at a post-tetanic count of 1 or 2. Drugs dosages were free according to each investigator's usual practice.
RESULTS:
Three hundred fifty-nine patients were enrolled onto the study. Time from reversal administration to TOFr to 0.9 is significantly faster in the sugammadex group than in the neostigmine group (shallow block: 2.2 vs. 6.9 min, respectively; P < 0.0001; deep block: 2.7 vs. 16.2 min, respectively; P < 0.0001). The number of patients with TOFr < 0.9 at 5, 10, and 20 min post-reversal agent administration was higher in the neostigmine than in the sugammadex group. Just five patients did not receive opioids. All patients were extubated in the operative room except for a single patient in the sugammadex group who was extubated following PACU admission.
CONCLUSIONS:
This real-life study confirms that reversal time is faster in patients receiving sugammadex than in those receiving neostigmine. TOFr < 0.9 20 min after reversal was only present in patients treated with neostigmine
Reversal of rocuronium induced neuromuscular block with sugammadex or neostigmine: a large observational study.
No full textA technique for measuring the pp->Z+X background to the H4l channel for the discovery of the Higgs Boson at LHC
No full textA method for simultaneously extracting the dominant pp to Z+X and pp to ZZ backgrounds in the H to 4l signal region from early ATLAS measurements, is proposed. The main focus is in predicting the yield of the Z boson background associated with two heavy quarks decaying to leptons. The proposed method is divided into two stages: an initial stage where a ZQQ and ZZ control region is defined, and a second stage where an extrapolation of the measured ZQQ and ZZ to the Higgs signal region is performed. It is found that the ZQQ background in the Higgs signal region can be estimated with 70% and 30% uncertainty for an integrated luminosity of 0.2pb−1 and 1fb−1 respectively. These uncertainties are dominated by the limited statistics in the ZQQ control region. The systematic uncertainties come from the knowledge of the distributions of the various discriminating variables used in the lepton identification. These distributions can be obtained from early data by exploiting the lateral and longitudinal segmentation of the LAr calorimeter, and the inner detector (TRT and silicon). The main result of this work is that direct measurements may provide the only path to the Higgs discovery in the H to 4l channel during the first years of LHC running
Nadiške doline in Kovačeva jama pri Robiču
No full textV Nadiških dolinah (severovzhodna Furlanija, Videmska pokrajina) potekajo raziskovanja Prazgodovinskih najdišč od konca 19. st. (karta 1). V dolinah reke Nadiže in njenih pritokov nahajajo previsi in jame, pod katerimi oz. v katerih so ohranjeni številni sledovi prebivanja 'judi v času kovinskih dob. Pomembna so zlasti jamska najdišča Velika jama, Ciondar des Paganis (občina Faedis), Kovačeva jama pri Robiču, Foran del Landri in Šusterjeva jama ter gradišče S. Quirino. Najstarejše najdbe so bile odkrite v Veliki jami (t. 1: 1-9).3 Na podlagi primerjave z najdbami Ljubljanskega barja in avstrijsko-madžarskega prostora (Wieselburg-Gata), kot tudi Tržaškega Krasa, jih lahko datiramo v eneolitik - zgodnjo bronasto dobo. Najdbe iz jame Ciondar des Paganis (t. 1: 10-18)4 kažejo, da gre za jamsko grobišče, ki je bilo že v davnini razdejano. Uvrščamo ga v starejšo bronasto dobo, ker je zaradi podobnih Cementov verjetno sočasno jamskim grobiščem na Tridentinskem in v Benečiji. V Kovačevi jami (imenovani tudi Turjeva jama in Grotta di S. Ilario) pri Robiču je začel izkopavati 1. 1890 C. Marchesetti,6 v naslednjih letih pa so v njej raziskovali člani Furlanskega speleološko-hidrološkega društva iz Vidma.7 Veliko večino najdb predstavljajo fragmenti keramike, ki imajo različno fakturo in v glavnem klekasto ostenje (t. 2-4, si. 2). Okras je redek, v glavnem gre za gladka plastična rebra. Pojavljajo se trakasti ročaji s konkavnima robovoma, t unelasti ročajčki in jezičasti držaji. Zdi se, da sodi to gradivo, ki ga lahko časovno opredelimo Samo na podlagi tipoloških primerjav z najdbami kraških in istrskih gradišč,8 v daljše obdobje razvite srednje bronaste dobe do konca mlajše oziroma do začetka končne bronaste dobe, ')• od 15. do začetka 12. st. pr. n. š. Ker je jasno, da je že v prazgodovini promet potekal predvsem po rečnih dolinah, menimo, da so kulturne prvine s področja severovzhodne Avstrije in Slovenije prodirale v Furlanijo prav skozi Nadiške doline
Author Correction: A portrait of the Higgs boson by the CMS experiment ten years after the discovery
No full textIn the version of this article initially published, CMS Collaboration author names, affiliations and acknowledgements were omitted and have now been included in the HTML and PDF versions of the articl
Search for a CP-odd Higgs boson decaying to Zh in pp collisions at root s=8 TeV with the ATLAS detector
No full textSee paper for full list of authors – 13 pages plus author list + cover pages (30 pages total), 5 figures, 2 tables, submitted to Phys. Lett. B, All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2013-06/International audienceA search for a heavy, CP-odd Higgs boson, , decaying into a boson and a 125 GeV Higgs boson, , with the ATLAS detector at the LHC is presented. The search uses proton--proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb. Decays of CP-even bosons to or pairs with the boson decaying to electron or muon pairs are considered, as well as decays with the boson decaying to neutrinos. No evidence for the production of an boson in these channels is found and the 95% confidence level upper limits derived for \sigma (gg\rightarrow A) \times \mbox{BR}(A \rightarrow Zh) \times \mbox{BR}(h \rightarrow f\bar{f}) are 0.098--0.013 pb for and 0.57--0.014 pb for in a range of 220--1000 GeV. The results are combined and interpreted in the context of two-Higgs doublet models
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