3,908 research outputs found

    CDF trigger final balance: Offline resolution at low level selections to fight against Tevatron increasing luminosity

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    Abstract The CDF detector at Tevatron collider is at present the most long-lasting high energy physics experiment. Since its first data taking in 1992 it has produced many results of primary importance, such as the discovery of top quark and, more recently, the observations of Bs oscillations and single-top production. None of them would have been possible without a fast and efficient trigger system. Based on a three level architecture, the CDF trigger takes decisions on simple calorimetric and tracking objects and assures both high efficiency on signal events and low dead time. It reduces the data flow rate from 2.53 MHz, the collision rate, to 150 Hz, the current limit on tape writing and is flexible enough to be easily adapted to the continuously growing instantaneous luminosity. In the last years the Tevatron instantaneous luminosity has rapidly increased and is now reaching 4 √ó 10 32 cm - 2 s - 1 . The CDF trigger system has been widely upgraded to cope with increasing trigger rates. The upgrade result is online reconstruction of missing transverse energy, jets and tracks with a quality comparable to the offline one. Jet energy and direction can be precisely determined and tracks can be subjected to 3-D reconstruction with good resolution. These upgrades reduce high trigger rates to acceptable levels and have provided invaluable tools to increase the purity of the collected samples. They also represent a helpful experience for LHC experiments where background rates will be much more demanding

    Top, W and Z: Experimental results

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    In this paper we will review the most recent experimental results obtained at Tevatron (Fermilab) on top and electroweak physics

    Many-core applications to online track reconstruction in HEP experiments

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    Interest in parallel architectures applied to real time selections is growing in High Energy Physics (HEP) experiments. In this paper we describe performance measurements of Graphic Processing Units (GPUs) and Intel Many Integrated Core architecture (MIC) when applied to a typical HEP online task: the selection of events based on the trajectories of charged particles. We use as benchmark a scaled-up version of the algorithm used at CDF experiment at Tevatron for online track reconstruction - the SVT algorithm - as a realistic test-case for low-latency trigger systems using new computing architectures for LHC experiment. We examine the complexity/performance trade-off in porting existing serial algorithms to many-core devices. Measurements of both data processing and data transfer latency are shown, considering different I/O strategies to/from the parallel devices.Comment: Proceedings for the 20th International Conference on Computing in High Energy and Nuclear Physics (CHEP); missing acks adde

    The estimation of neutrino fluxes produced by proton-proton collisions at s=14\sqrt{s}=14 TeV of the LHC

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    Intense and collimated neutrino beams are produced by charm and beauty particle decays from proton-proton collisions at the LHC. A neutrino experiment would be run parasitically without interrupting the LHC physics program during the collider run. We estimate the neutrino fluxes from proton-proton collisions at s=14\sqrt{s}=14 TeV of the LHC with the designed luminosity, 10^{34} \lumi. By mounting about 200 tons of fiducial volume of a neutrino detector at 300 \m away from the interaction point, about 150,000 of charged current neutrino events per year can be observable.Comment: 8 pages, Accepted in JHE

    High-precision measurement of the W boson mass with the CDF II detector

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    The mass of the W boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. The Higgs boson was the last missing component of the model. After observation of the Higgs boson, a measurement of the W boson mass provides a stringent test of the model. We measure the W boson mass, MW, using data corresponding to 8.8 inverse femtobarns of integrated luminosity collected in proton-antiproton collisions at a 1.96 tera-electron volt center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider. A sample of approximately 4 million W boson candidates is used to obtain [Formula: see text], the precision of which exceeds that of all previous measurements combined (stat, statistical uncertainty; syst, systematic uncertainty; MeV, mega-electron volts; c, speed of light in a vacuum). This measurement is in significant tension with the standard model expectation

    First LHCb measurement with data from the LHC Run 2

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    LHCb has recently introduced a novel real-time detector alignment and calibration strategy for the Run 2. Data collected at the start of each LHC Ô¨Āll are processed in few minutes and used to update the alignment. On the other hand, the calibration constants will be evaluated for each run of data taking. An increase in the CPU and disk capacity of the event Ô¨Ālter farm, combined with improvements to the reconstruction software, allow for eÔ¨Écient, exclusive selections already in the Ô¨Ārst stage of the High Level Trigger (HLT1), while the second stage, HLT2, performs complete, oÔ¨Ąine-quality, event reconstruction. In Run 2, LHCb will collect the largest data sample of charm mesons ever recorded. Novel data processing and analysis techniques are required to maximise the physics potential of this data sample with the available computing resources, taking into account data preservation constraints. In this write-up, we describe the full analysis chain used to obtain important results analysing the data collected in proton-proton collisions in 2015, such as the J/Ōą and open charm production cross-sections, and consider the further steps required to obtain real-time results after the LHCb upgrade

    The prevalence and predictors of comorbid bipolar disorder and obsessive-compulsive disorder: A systematic review and meta-analysis

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    Abstract Background: Although some authors have recently investigated the co-occurrence of anxiety and bipolar disorders, the topic remains insufficiently studied. Defining the prevalence and predictors of BD-OCD comorbidity has important nosological, clinical and therapeutic implications. Methods: A systematic review and meta-analysis was conducted on the prevalence and predictors of comorbid BD-OCD. Relevant papers published through March 30th, 2015 were identified searching the electronic databases MEDLINE, Embase, PsycINFO and the Cochrane Library. Results: 46 articles met inclusion criteria. The pooled prevalence of OCD in BD was 17.0% (95% CI 12.7-22.4%), which was comparable to the results reported by the pooled prevalence of BD in OCD (18.35%, 95% CI 13.2-24.8%). With regard to OCD-BD predictors, a higher mean age predicted a lower prevalence of OCD in BD patients. Sub group meta-analyses reported higher OCD prevalence rates in BD children and adolescents (24.2%, compared to 13.5% in adults), in BD-I patients (24.6%, compared to 13.6% in mixed BD patients), and among population-based studies (22.2%, compared to 13.2% in hospital-based studies). Limitations: Most studies use retrospective assessment scales with low sensitivity in discriminating true ego-dystonic obsessions from depressive ruminations that may bias results towards an overestimation of obsessive symptom prevalence. Conclusions: This first systematic review and meta-analysis of the prevalence and predictors of comorbid BD-OCD confirms that BD-OCD comorbidity is a common condition in psychiatry with children and adolescents and BD-I patients as the most affected subgroups

    Measurement of the WW and WZ production cross section using final states with a charged lepton and heavy-flavor jets in the full CDF Run II data set

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    We present a measurement of the total WW and WZ production cross sections in p (p) over bar collision at root s = 1.96 TeV, in a final state consistent with leptonic W boson decay and jets originating from heavy-flavor quarks from either a W or a Z boson decay. This analysis uses the full data set collected with the CDF II detector during Run II of the Tevatron collider, corresponding to an integrated luminosity of 9.4 fb(-1). An analysis of the dijet mass spectrum provides 3.7 sigma evidence of the summed production processes of either WW or WZ bosons with a measured total cross section of sigma(WW+WZ) = 13.7 +/- 3.9 pb. Independent measurements of the WW and WZ production cross sections are allowed by the different heavy- flavor decay patterns of the W and Z bosons and by the analysis of secondary- decay vertices reconstructed within heavy- flavor jets. The productions of WW and of WZ dibosons are independently seen with significances of 2.9s and 2.1s, respectively, with total cross sections of sigma(WW) = 9.4 +/- 4.2 pb and sigma(WZ) = 3.7(-2.2)(+2.5) pb. The measurements are consistent with standard- model predictions.Peer reviewe
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