Papers by C. De La Taille
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2005
In the years between 2000 and 2002 several pre-series and series modules of the ATLAS EM barrel a... more In the years between 2000 and 2002 several pre-series and series modules of the ATLAS EM barrel and end-cap calorimeter were exposed to electron, photon and pion beams. The performance of the calorimeter with respect to its finely segmented first sampling has been studied. The polar angle resolution has been found to be in the range 50 − 60 (mrad)/ E (GeV). The π 0 rejection has been measured to be about 3.5 for 90% photon selection efficiency at p T = 50 GeV/c. e-π separation studies have indicated that a pion fake rate of (0.07-0.5)% can be achieved while maintaining 90% electron identification efficiency for energies up to 40 GeV.
√ s = 8 TeV with the ATLAS detector ✩ .ATLAS Collaboration a r t i c l e i n f o a b s t r a c t
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2011
Physical Review D - Particles, Fields, Gravitation and Cosmology, 2011
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2011
A search for long-lived charged particles reaching the muon spectrometer is performed using a dat... more A search for long-lived charged particles reaching the muon spectrometer is performed using a data sample of 37 pb −1 from pp collisions at √ s = 7 TeV collected by the ATLAS detector at the LHC in 2010. No excess is observed above the estimated background. Stableτ sleptons are excluded at 95% CL up to a mass of 136 GeV, in GMSB models with N 5 = 3, m messenger = 250 TeV, sign(µ) = 1 and tanβ = 5. Electroweak production of sleptons is excluded up to a mass of 110 GeV. Gluino R-hadrons in a generic interaction model are excluded up to masses of 530 GeV to 544 GeV depending on the fraction of R-hadrons produced asg-balls.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2011
A measurement of the cross-section for ϒ(1S) → µ + µ − production in proton-proton collisions at ... more A measurement of the cross-section for ϒ(1S) → µ + µ − production in proton-proton collisions at centre of mass energy of 7 TeV is presented. The cross-section is measured as a function of the ϒ(1S) transverse momentum in two bins of rapidity, |y ϒ(1S) | < 1.2 and 1.2 < |y ϒ(1S) | < 2.4. The measurement requires that both muons have transverse momentum p µ T > 4 GeV and pseudorapidity |η µ | < 2.5 in order to reduce theoretical uncertainties on the acceptance, which depend on the poorly known polarization. The results are based on an integrated luminosity of 1.13 pb −1 , collected with the ATLAS detector at the Large Hadron Collider. The cross-section measurement is compared to theoretical predictions: it agrees to within a factor of two with a prediction based on the NRQCD model including colour-singlet and colour-octet matrix elements as implemented in PYTHIA while it disagrees by up to a factor of ten with the next-to-leading order prediction based on the colour-singlet-model.
New Journal of Physics, 2011
A search for new physics in dijet mass and angular distributions in pp collisions at √ s= 7 TeV m... more A search for new physics in dijet mass and angular distributions in pp collisions at √ s= 7 TeV measured with the ATLAS detector The ATLAS Collaboration Abstract. A search for new interactions and resonances produced in LHC proton-proton ( pp) collisions at a centre-of-mass energy √ s = 7 TeV was performed with the ATLAS detector. Using a dataset with an integrated luminosity of 36 pb −1 , dijet mass and angular distributions were measured up to dijet masses of ∼3.5 TeV and were found to be in good agreement with Standard Model predictions. This analysis sets limits at 95% CL on various models for new physics: an excited quark is excluded for mass between 0.60 and 2.64 TeV, an axigluon hypothesis is excluded for axigluon masses between 0.60 and 2.10 TeV and quantum black holes are excluded in models with six extra space-time dimensions for quantum gravity scales between 0.75 and 3.67 TeV. Production cross section limits as a function of dijet mass are set using a simplified Gaussian signal model to facilitate comparisons with other hypotheses. Analysis of the dijet angular distribution using a novel technique simultaneously employing the dijet mass excludes quark contact interactions with a compositeness scale below 9.5 TeV.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2012
A search for production of supersymmetric particles in final states containing jets, missing tran... more A search for production of supersymmetric particles in final states containing jets, missing transverse momentum, and at least one hadronically decaying τ lepton is presented. The data were recorded by the ATLAS experiment in s= 7 TeV proton–proton collisions at the Large Hadron Collider. No excess above the Standard Model background expectation was observed in 2.05 fb− 1 of data. The results are interpreted in the context of gauge mediated supersymmetry breaking models with Mmess= 250 TeV, N5= 3, μ&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0, and Cgrav= 1. The ...
Physical Review D - Particles, Fields, Gravitation and Cosmology, 2012
European Physical Journal C, 2012
This letter reports on a search for hypothetical heavy neutrinos, N, and right-handed gauge boson... more This letter reports on a search for hypothetical heavy neutrinos, N, and right-handed gauge bosons, W R , in events with high transverse momentum objects which include two reconstructed leptons and at least one hadronic jet. The results were obtained from data corresponding to an integrated luminosity of 2.1 fb −1 collected in proton-proton collisions at √ s = 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. No excess above the Standard Model background expectation is observed. Excluded mass regions for Majorana and Dirac neutrinos are presented using two approaches for interactions that violate lepton and lepton-flavor numbers. One approach uses an effective operator framework, the other approach is guided by the Left-Right Symmetric Model. The results described in this letter represent the most stringent limits to date on the masses of heavy neutrinos and W R bosons obtained in direct searches.
Physical Review D - Particles, Fields, Gravitation and Cosmology, 2012
The ATLAS detector is used to search for excited leptons in the electromagnetic radiative decay c... more The ATLAS detector is used to search for excited leptons in the electromagnetic radiative decay channel ' à ! '. Results are presented based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 2:05 fb À1 . No evidence for excited leptons is found, and limits are set on the compositeness scale à as a function of the excited lepton mass m ' à . In the special case where à ¼ m ' à , excited electron and muon masses below 1.87 TeV and 1.75 TeV are excluded at 95% C.L., respectively.
European Physical Journal C, 2012
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2012
Abstract: A search for a heavy Standard Model Higgs boson decaying via H-&amp;amp;gt; ZZ-&... more Abstract: A search for a heavy Standard Model Higgs boson decaying via H-&amp;amp;gt; ZZ-&amp;amp;gt; llqq, where l= e or mu, is presented. The search uses a data set of pp collisions at sqrt (s)= 7 TeV, corresponding to an integrated luminosity of 4.7 fb^-1 collected in 2011 by the ATLAS detector at the CERN LHC. No significant excess of events above the estimated background is found. Upper limits at 95% confidence level on the production cross section of a Higgs boson with a mass in the range between 200 and 600 GeV are derived. A Standard Model ...
European Physical Journal C, 2012
European Physical Journal C, 2012
Proton-proton collisions at √ s = 7 TeV and heavy ion collisions at √ s NN = 2.76 TeV were produc... more Proton-proton collisions at √ s = 7 TeV and heavy ion collisions at √ s NN = 2.76 TeV were produced by the LHC and recorded using the ATLAS experiment's trigger system in 2010. The LHC is designed with a maximum bunch crossing rate of 40 MHz and the ATLAS trigger system is designed to record approximately 200 of these per second. The trigger system selects events by rapidly identifying signatures of muon, electron, photon, tau lepton, jet, and B meson candidates, as well as using global event signatures, such as missing transverse energy. An overview of the ATLAS trigger system, the evolution of the system during 2010 and the performance of the trigger system components and selections based on the 2010 collision data are shown. A brief outline of plans for the trigger system in 2011 is presented.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2012
A measurement of the production cross-section for top quark pairs (tt) in pp collisions at √ s = ... more A measurement of the production cross-section for top quark pairs (tt) in pp collisions at √ s = 7 TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron e or muon µ) with large missing transverse energy and at least four jets, and dilepton (ee, µµ or eµ) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb −1 , 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-tt Standard Model processes are estimated using data-driven methods and determined to be 12.2 ± 3.9 events and 2.5 ± 0.6 events, respectively. The kinematic properties of the selected events are consistent with SM tt production. The inclusive top quark pair production cross-section is measured to be
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2012
European Physical Journal C, 2012
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2012
This Letter presents evidence for the associated production of a W boson and a top quark using 2.... more This Letter presents evidence for the associated production of a W boson and a top quark using 2.05 fb −1 of pp collision data at √ s = 7 TeV accumulated with the ATLAS detector at the LHC. The analysis is based on the selection of the dileptonic final states with events featuring two isolated leptons, electron or muon, with significant transverse missing momentum and at least one jet. An approach based on boosted decision trees has been developed to improve the discrimination of single top-quark Wt events from background. A template fit to the final classifier distributions is performed to determine the cross-section. The result is incompatible with the background-only hypothesis at the 3.3σ level, the expected sensitivity assuming the Standard Model production rate being 3.4σ. The corresponding cross-section is determined and found to be σ Wt = 16.8 ± 2.9 (stat) ± 4.9 (syst) pb, in good agreement with the Standard Model expectation. From this result the CKM matrix element |V tb | = 1.03 +0.16 −0.19 is derived assuming that the Wt production through |V ts | and |V td | is small.
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Papers by C. De La Taille