High energy physics experiments periodically reprocess data, in order to take advantage of improved understanding of the detector and the data processing code. Between February and May 2007, the ...DZero experiment has reprocessed a substantial fraction of its dataset. This consists of half a billion events, corresponding to about 100 TB of data, organized in 300,000 files. The activity utilized resources from sites around the world, including a dozen sites participating to the Open Science Grid consortium (OSG). About 1,500 jobs were run every day across the OSG, consuming and producing hundreds of Gigabytes of data. Access to OSG computing and storage resources was coordinated by the SAM-Grid system. This system organized job access to a complex topology of data queues and job scheduling to clusters, using a SAM-Grid to OSG job forwarding infrastructure. For the first time in the lifetime of the experiment, a data intensive production activity was managed on a general purpose grid, such as OSG. This paper describes the implications of using OSG, where all resources are granted following an opportunistic model, the challenges of operating a data intensive activity over such large computing infrastructure, and the lessons learned throughout the project.
We present measurements of the cross sections for the two main production modes of single top quarks in pp¯ collisions at s=1.96 TeV in the Run II data collected with the D0 detector at the Fermilab ...Tevatron Collider, corresponding to an integrated luminosity of 9.7 fb−1. The s-channel cross section is measured to be σ(pp¯→tb+X)=1.10−0.31+0.33 pb with no assumptions on the value of the t-channel cross section. Similarly, the t-channel cross section is measured to be σ(pp¯→tqb+X)=3.07−0.49+0.54 pb. We also measure the s+t combined cross section as σ(pp¯→tb+X,tqb+X)=4.11−0.55+0.60 pb and set a lower limit on the CKM matrix element |Vtb|>0.92 at 95% C.L., assuming mt=172.5 GeV. The probability to measure a cross section for the s channel at the observed value or higher in the absence of signal is 1.0×10−4, corresponding to a significance of 3.7 standard deviations.
We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to ...parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance δR in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of δR and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb -1 collected with the D0 detector at the Fermilab Tevatron Collider in pp- collisions at s=1.96 TeV. The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50-400 GeV.
We use higher-order quantum chromodynamics calculations to extract the mass of the top quark from the t (t) over bar cross section measured in the lepton + jets channel in p (p) over bar collisions ...at root s = 1.96 TeV using 5.3 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. The extracted top quark pole mass and (MS) over bar mass are compared to the current Tevatron average top quark mass obtained from direct measurements.
Jet energy scale determination in the D0 experiment Abbott, B.; Adams, M.; Adams, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2014, Letnik:
763
Journal Article
Recenzirano
Odprti dostop
The calibration of jet energy measured in the D0 detector is presented, based on pp¯ collisions at a center-of-mass energy of 1.96TeV at the Fermilab Tevatron collider. Jet energies are measured ...using a sampling calorimeter composed of uranium and liquid argon as the passive and active media, respectively. This paper describes the energy calibration of jets performed with γ+jet, Z+jet and dijet events, with jet transverse momentum pT>6GeV and pseudorapidity range |η|<3.6. The corrections are measured separately for data and simulation, achieving a precision of 1.4–1.8% for jets in the central part of the calorimeter and up to 3.5% for the jets with pseudorapidity |η|=3.0. Specific corrections are extracted to enhance the description of jet energy in simulation and in particular of the effects due to the flavor of the parton originating the jet, correcting biases up to 3–4% in jets with low pT originating from gluons and up to 6–8% in jets from b quarks.
Search for the rare decay Bs0→μ+μ Adams, M.; Alexeev, G.D.; Alton, A. ...
Physics letters. B,
10/2010, Letnik:
693, Številka:
5
Journal Article
Recenzirano
Odprti dostop
We present the results of a search for the flavor changing neutral current decay Bs0→μ+μ− using 6.1 fb−1 of pp¯ collisions at s=1.96 TeV collected by the D0 experiment at the Fermilab Tevatron ...Collider. The observed number of Bs0 candidates is consistent with background expectations. The resulting upper limit on the branching fraction is B(Bs0→μ+μ−)<5.1×10−8 at the 95% C.L. This limit is a factor of 2.4 better than that of the previous D0 analysis and the best limit to date.
A data sample corresponding to an integrated luminosity of 2.1 fb(-1) collected by the D phi detector at the Fermilab Tevatron Collider was analyzed to search for squarks and gluinos produced in p ...(p) over bar collisions at a center-of-mass energy of 1.96 TeV. No evidence for the production of such particles was observed in topologies involving jets and missing transverse energy, and 95% C.L. lower limits of 379 GeV and 308 GeV were set on the squark and gluino masses, respectively, within the framework of minimal supergravity with tan beta = 3, A(0) = 0, and mu < 0. The corresponding previous limits are improved by 54 GeV and 67 GeV.
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