The European Physical Journal C

http://link.springer.com/journal/10052

List of Papers (Total 2,952)

Monte Carlo integration on GPU

We use a graphics processing unit (GPU) for fast computations of Monte Carlo integrations. Two widely used Monte Carlo integration programs, VEGAS and BASES, are parallelized for running on a GPU. By using W + plus multi-gluon production processes at LHC, we test the integrated cross sections and execution time for programs written in FORTRAN and running in the CPU and those ...

Single-top Wt-channel production matched with parton showers using the POWHEG method

We present results for the next-to-leading order calculation of single-top Wt-channel production interfaced to Shower Monte Carlo programs, implemented according to the POWHEG method. A comparison with MC@NLO is carried out. Results obtained using the PYTHIA shower are also shown and the effect of typical cuts is briefly discussed.

Measurement of inclusive jet and dijet cross sections in proton-proton collisions at 7 TeV centre-of-mass energy with the ATLAS detector

Jet cross sections have been measured for the first time in proton-proton collisions at a centre-of-mass energy of 7 TeV using the ATLAS detector. The measurement uses an integrated luminosity of 17 nb−1 recorded at the Large Hadron Collider. The anti-k t algorithm is used to identify jets, with two jet resolution parameters, R=0.4 and 0.6. The dominant uncertainty comes from the ...

Jet reconstruction in heavy ion collisions

We examine the problem of jet reconstruction at heavy-ion colliders using jet-area-based background subtraction tools as provided by FastJet. We use Monte Carlo simulations with and without quenching to study the performance of several jet algorithms, including the option of filtering, under conditions corresponding to RHIC and LHC collisions. We find that most standard algorithms ...

Percolation of color sources and the equation of state of QGP in central Au–Au collisions at \(\sqrt{s_{\mathit{NN}}}=200\) GeV

The Color String Percolation Model (CSPM) is used to determine the equation of state (EOS) of the Quark–Gluon Plasma (QGP) produced in central Au–Au collisions at \(\sqrt{s_{\mathit{NN}}} = 200\) A GeV using STAR data at RHIC. When the initial density of interacting colored strings exceeds the 2D percolation threshold a cluster is formed, which defines the onset of color ...

Measurement of charm and beauty jets in deep inelastic scattering at HERA

Measurements of cross sections for events with charm and beauty jets in deep inelastic scattering at HERA are presented. Events with jets of transverse energy \(E_{T}^{\mathrm{jet}}>6\) GeV and pseudorapidity −1.0<η jet<1.5 in the laboratory frame are selected in the kinematic region of photon virtuality Q 2>6 GeV2 and inelasticity variable 0.07<y<0.625. Measurements are also made ...

A fresh look at η 2(1645), η 2(1870), η 2(2030) and f 2(1910) in \(\bar{p}p \to \eta \pi ^{0}\pi ^{0}\pi ^{0}\)

There is a large discrepancy between results of Crystal Barrel and WA102 for the branching ratio R=BR[η 2(1870)→a 2(1320)π]/BR[η 2(1870)→f 2(1270)η]. An extensive re-analysis of the Crystal Barrel data redetermines branching ratios for decays of η 2(1870), η 2(1645), η 2(2030) and f 2(1910). This re-analysis confirms a small value for R of 1.60±0.39, inconsistent with the value ...

Same sign WW scattering process as a probe of Higgs boson in pp collision at \(\sqrt{s}=10\) TeV

WW scattering is an important process to study electroweak symmetry breaking in the Standard Model at the LHC, in which the Higgs mechanism or other new physics processes must intervene to preserve the unitarity of the process below 1 TeV. This channel is expected to be one of the most sensitive to determine whether the Higgs boson exists. In this paper, the final state with two ...

Variant supercurrents and Noether procedure

Consistent supercurrent multiplets are naturally associated with linearized off-shell supergravity models. In S.M. Kuzenko, J. High Energy Phys. 1004, 022 (2010) we presented the hierarchy of such supercurrents which correspond to all the models for linearized 4D \(\mathcal{N}=1\) supergravity classified a few years ago. Here we analyze the correspondence between the most general ...

Numerical evaluation of tensor Feynman integrals in Euclidean kinematics

For the investigation of higher order Feynman integrals, potentially with tensor structure, it is highly desirable to have numerical methods and automated tools for dedicated, but sufficiently ‘simple’ numerical approaches. We elaborate two algorithms for this purpose which may be applied in the Euclidean kinematical region and in d=4−2ε dimensions. One method uses Mellin–Barnes ...

HELAS and MadGraph with spin-3/2 particles

Fortran subroutines to calculate helicity amplitudes with massive spin-3/2 particles, such as massive gravitinos, which couple to the standard model and supersymmetric particles via the supercurrent, are added to the HELAS (HELicity Amplitude Subroutines) library. They are coded in such a way that arbitrary amplitudes with external gravitinos can be generated automatically by ...

Reevaluation of the hadronic contributions to the muon g−2 and to \(\alpha (M^{2}_{Z})\)

We reevaluate the hadronic contributions to the muon magnetic anomaly, and to the running of the electromagnetic coupling constant at the Z-boson mass. We include new π + π − cross-section data from KLOE, all available multi-hadron data from BABAR, a reestimation of missing low-energy contributions using results on cross sections and process dynamics from BABAR, a reevaluation of ...

Readiness of the ATLAS liquid argon calorimeter for LHC collisions

The ATLAS liquid argon calorimeter has been operating continuously since August 2006. At this time, only part of the calorimeter was readout, but since the beginning of 2008, all calorimeter cells have been connected to the ATLAS readout system in preparation for LHC collisions. This paper gives an overview of the liquid argon calorimeter performance measured in situ with random ...

The CCFM Monte Carlo generator CASCADE Version 2.2.03

Cascade is a full hadron level Monte Carlo event generator for ep, γp and \(p\bar{p}\) and pp processes, which uses the CCFM evolution equation for the initial state cascade in a backward evolution approach supplemented with off-shell matrix elements for the hard scattering. A detailed program description is given, with emphasis on parameters the user wants to change and common ...

Drift Time Measurement in the ATLAS Liquid Argon Electromagnetic Calorimeter using Cosmic Muons

The ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons. In particular, the drift time of the ionization electrons is measured and used to assess the intrinsic uniformity of the calorimeter gaps and estimate its impact on the constant term of the energy resolution. The drift times of electrons in the cells of the ...

Commissioning of the ATLAS Muon Spectrometer with cosmic rays

The ATLAS detector at the Large Hadron Collider has collected several hundred million cosmic ray events during 2008 and 2009. These data were used to commission the Muon Spectrometer and to study the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs. We present the performance in the ...

CMS tracking performance results from early LHC operation

The first LHC pp collisions at centre-of-mass energies of 0.9 and 2.36 TeV were recorded by the CMS detector in December 2009. The trajectories of charged particles produced in the collisions were reconstructed using the all-silicon Tracker and their momenta were measured in the 3.8 T axial magnetic field. Results from the Tracker commissioning are presented including studies of ...

First measurement of the underlying event activity at the LHC with \(\sqrt{s} = 0.9\) TeV

A measurement of the underlying activity in scattering processes with p T scale in the GeV region is performed in proton–proton collisions at \(\sqrt{s} = 0.9\) TeV, using data collected by the CMS experiment at the LHC. Charged particle production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. ...

The ATLAS Inner Detector commissioning and calibration

The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance ...

Cross-sections of large-angle hadron production in proton– and pion–nucleus interactions VI: carbon nuclei and beam momenta from ±3 GeV/c to ±15 GeV/c

We report on double-differential inclusive cross-sections of the production of secondary protons, charged pions, and deuterons, in the interactions with a 5% λ int thick stationary carbon target, of proton and pion beams with momentum from ±3 GeV/c to ±15 GeV/c. Results are given for secondary particles with production angles 20°<θ<125°. Cross-sections on carbon nuclei are compared ...

The ATLAS Simulation Infrastructure

The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the ...

Readiness of the ATLAS Tile Calorimeter for LHC collisions

The Tile hadronic calorimeter of the ATLAS detector has undergone extensive testing in the experimental hall since its installation in late 2005. The readout, control and calibration systems have been fully operational since 2007 and the detector has successfully collected data from the LHC single beams in 2008 and first collisions in 2009. This paper gives an overview of the Tile ...

Inclusive dijet cross sections in neutral current deep inelastic scattering at HERA

Single- and double-differential inclusive dijet cross sections in neutral current deep inelastic ep scattering have been measured with the ZEUS detector using an integrated luminosity of 374 pb−1. The measurement was performed at large values of the photon virtuality, Q 2, between 125 and 20 000 GeV2. The jets were reconstructed with the k T cluster algorithm in the Breit reference ...

Probing new physics models of neutrinoless double beta decay with SuperNEMO

The possibility to probe new physics scenarios of light Majorana neutrino exchange and right-handed currents at the planned next generation neutrinoless double β decay experiment SuperNEMO is discussed. Its ability to study different isotopes and track the outgoing electrons provides the means to discriminate different underlying mechanisms for the neutrinoless double β decay by ...

Relating multihadron production in hadronic and nuclear collisions

The energy-dependence of charged particle mean multiplicity and pseudorapidity density at midrapidity measured in nucleus–nucleus and (anti)proton–proton collisions are studied in the entire available energy range. The study is performed using a model, which considers the multiparticle production process according to the dissipating energy of the participants and their types, ...