1,372 research outputs found
A Performance Comparison Using HPC Benchmarks: Windows HPC Server 2008 and Red Hat Enterprise Linux 5
This document was developed with support from the National Science Foundation (NSF) under Grant No. 0910812 to Indiana University for âFutureGrid: An Experimental, High-Performance Grid Test-bed.â Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.A collection of performance benchmarks have been run on an IBM System X iDataPlex cluster using two different operating systems. Windows HPC Server 2008 (WinHPC) and Red Hat Enterprise Linux v5.4 (RHEL5) are compared using SPEC MPI2007 v1.1, the High Performance Computing Challenge (HPCC) and National Science Foundation (NSF) acceptance test benchmark suites. Overall, we find the performance of WinHPC and RHEL5 to be equivalent but significant performance differences exist when analyzing specific applications. We focus on presenting the results from the application benchmarks and include the results of the HPCC microbenchmark for completeness
Search for Higgs bosons decaying into new spin-0 or spin-1 particles in four-lepton final states with the ATLAS detector with 139 fbâ1 of pp collision data at âs = 13 TeV
Searches are conducted for new spin-0 or spin-1 bosons using events where a Higgs boson with mass 125 GeV decays into four leptons (â = e, ÎŒ). This decay is presumed to occur via an intermediate state which contains two on-shell, promptly decaying bosons: H â XX/ZX â 4â, where the new boson X has a mass between 1 and 60 GeV. The search uses pp collision data collected with the ATLAS detector at the LHC with an integrated luminosity of 139 fbâ1 at a centre-of-mass energy sâ = 13 TeV. The data are found to be consistent with Standard Model expectations. Limits are set on fiducial cross sections and on the branching ratio of the Higgs boson to decay into XX/ZX, improving those from previous publications by a factor between two and four. Limits are also set on mixing parameters relevant in extensions of the Standard Model containing a dark sector where X is interpreted to be a dark boson
Saturation in diffractive deep inelastic eA scattering
In this paper we investigate the saturation physics in diffractive deep
inelastic electron-ion scattering. We estimate the energy and nuclear
dependence of the ratio and predict the x_{\pom}
and behavior of the nuclear diffractive structure function
. Moreover, we analyze the ratio
,
which probes the nuclear dependence of the structure of the Pomeron. We show
that saturation physics predicts that approximately 37 % of the events observed
at eRHIC should be diffractive.Comment: 15 pages, 7 figures. Version to be published in the European Physical
Journal
Operation and performance of the ATLAS semiconductor tracker in LHC Run 2
The semiconductor tracker (SCT) is one of the tracking systems for charged particles in the ATLAS detector. It consists of 4088 silicon strip sensor modules. During Run 2 (2015â2018) the Large Hadron Collider delivered an integrated luminosity of 156 fb-1 to the ATLAS experiment at a centre-of-mass proton-proton collision energy of 13 TeV. The instantaneous luminosity and pile-up conditions were far in excess of those assumed in the original design of the SCT detector. Due to improvements to the data acquisition system, the SCT operated stably throughout Run 2. It was available for 99.9% of the integrated luminosity and achieved a data-quality efficiency of 99.85%. Detailed studies have been made of the leakage current in SCT modules and the evolution of the full depletion voltage, which are used to study the impact of radiation damage to the modules
Search for neutral long-lived particles in pp collisions at âs = 13 TeV that decay into displaced hadronic jets in the ATLAS calorimeter
A search for decays of pair-produced neutral long-lived particles (LLPs) is presented using 139 fbâ1 of proton-proton collision data collected by the ATLAS detector at the LHC in 2015â2018 at a centre-of-mass energy of 13 TeV. Dedicated techniques were developed for the reconstruction of displaced jets produced by LLPs decaying hadronically in the ATLAS hadronic calorimeter. Two search regions are defined for different LLP kinematic regimes. The observed numbers of events are consistent with the expected background, and limits for several benchmark signals are determined. For a SM Higgs boson with a mass of 125 GeV, branching ratios above 10% are excluded at 95% confidence level for values of c times LLP mean proper lifetime in the range between 20 mm and 10 m depending on the model. Upper limits are also set on the cross-section times branching ratio for scalars with a mass of 60 GeV and for masses between 200 GeV and 1 TeV
Measurements of Higgs boson production cross-sections in the H â Ï+Ïâ decay channel in pp collisions at âs = 13 TeV with the ATLAS detector
Measurements of the production cross-sections of the Standard Model (SM) Higgs boson (H) decaying into a pair of Ï-leptons are presented. The measurements use data collected with the ATLAS detector from pp collisions produced at the Large Hadron Collider at a centre-of-mass energy of âs = 13 TeV, corresponding to an integrated luminosity of 139 fbâ1. Leptonic (Ï â âÎœâÎœÏ) and hadronic (Ï â hadrons ÎœÏ) decays of the Ï-lepton are considered. All measurements account for the branching ratio of H â ÏÏ and are performed with a requirement |yH| < 2.5, where yH is the true Higgs boson rapidity. The cross-section of the pp â H â ÏÏ process is measured to be 2.94 ± 0.21(stat)+0.37â0.32(syst) pb, in agreement with the SM prediction of 3.17 ± 0.09 pb. Inclusive cross-sections are determined separately for the four dominant production modes: 2.65 ± 0.41(stat)+0.91â0.67(syst) pb for gluon-gluon fusion, 0.197 ± 0.028(stat)+0.032â0.026(syst) pb for vector-boson fusion, 0.115 ± 0.058(stat)+0.042â0.040(syst) pb for vector-boson associated production, and 0.033 ± 0.031(stat)+0.022â0.017(syst) pb for top-quark pair associated production. Measurements in exclusive regions of the phase space, using the simplified template cross-section framework, are also performed. All results are in agreement with the SM predictions
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