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Bertrand Laforge

Bertrand Laforge
Sorbonne Université, Paris, France · Laboratoire de Physique Nucléaire et des Hautes Energies - Institut Lagrange de Paris - UFR 925

Habilitation à Diriger des recherches (2004), PhD in particle physics (1997), Engineer in instrumentation (1993)

About

722
Publications
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Introduction
I work on the ATLAS experiment @ CERN. In 2012, we have discovered a new particle very likely to be the Higgs boson ! We now know the boson is very likely to be a 0+ state that couples to SM particles as expected. Rare decays of the Higgs are still to be observed and an experimental proof of Higgs boson autocoupling is still pending. With the current LHC run 2 @13TeV, I search for possible couplings between the Higgs sector and a potential Dark Matter sector.
Additional affiliations
September 1999 - February 2010
Sorbonne Université
Position
  • SImbioPhys
Description
  • Simulation numérique de la différenciation cellulaire - Biologie thérique - Liens entre lois physique et organisation en biologie.
September 1997 - present
Sorbonne Université
Position
  • ATLAS experiment - Higgs Boson Search (and found !)
September 1994 - August 1997
Atomic Energy and Alternative Energies Commission
Position
  • Doctorant
Description
  • Etude de la capacité de QCD à décrire les événements à grand gap de rapidité observés à HERA dans les collisions e-p. Il s'agit de collisions dures dans lesquelles le proton reste (quasiment) intact, ce qui est très intriguant à première vue.

Publications

Publications (722)
Article
Full-text available
A search for the Standard Model Higgs boson in proton–proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb −1 collected at √ s = 7 TeV in 2011 and 5.8 fb −1 at √ s = 8 TeV in 2012. Individual searches in the channels H → Z Z (*) → 4, H → γ γ and H → W W (*...
Article
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A large amount of data demonstrating the stochastic nature of gene expression and cell differentiation has accumulated during the last 40 years. These data suggest that a gene in a cell always has a certain probability of being activated at any time and that instead of leading to on and off switches in an all-or-nothing fashion, the concentration o...
Article
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The construction and performance of the barrel pre-series module 0 of the future ATLAS electromagnetic calorimeter at the LHC is described. The signal reconstruction and performance of ATLAS-like electronics has been studied. The signal to noise ratio for muons has been found to be 7.11+-0.07. An energy resolution of better than 9.5% GeV^1/2/sqrt{E...
Article
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A combined search for the Standard Model Higgs boson with the ATLAS experiment at the LHC using datasets corresponding to integrated luminosities from 1.04 fb-1 to 4.9 fb-1 of pp collisions collected at s=7 TeV is presented. The Higgs boson mass ranges 112.9-115.5 GeV, 131-238 GeV and 251-466 GeV are excluded at the 95% confidence level (CL), while...
Article
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The introduction of extra space dimensions in the theory could be an elegant way tovsolve the hierarchy problem. There could even be one energy scale at which all interactions could unify. The limits coming from our knowledge of the gravitation at low distance allow this energy scale to be as low as few TeV. This situation is extremely interesting...
Conference Paper
Particle physics experiments deal with a huge volume of information and a complex sequential processing chain for online selection (trigger) of events. In the ATLAS experiment at the Large Hadron Collider (LHC), the trigger system is responsible for choosing the events that will be recorded on permanent media for future analysis and operates sequen...
Conference Paper
Full-text available
O ATLAS é o maior experimento do complexo do acelerador de partículas LHC no CERN. Está localizado em um dos pontos de colisão no túnel do acelerador e é composto de um conjunto de sub-detectores especializados para caracterizar as partículas produzidas nas colisões do LHC. Um desses detectores especializados é o calorímetro de Argônio Líquido (LAr...
Preprint
Full-text available
This note summarizes the activities and the scientific and technical perspectives of the Laboratoire de Physique Nucleaire et de Hautes Energies (LPNHE) at Sorbonne University, Paris. Although the ESPP is specifically aimed at particle physics, we discuss in this note in parallel the three scientific lines developed at LPNHE (Particle Physics, Astr...
Article
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A measurement of the fragmentation functions of jets into charged particles in p+Pb collisions and pp collisions is presented. The analysis utilizes 28 nb⁻¹ of p+Pb data and 26 pb⁻¹ of pp data, both at sNN= 5.02 TeV, collected in 2013 and 2015, respectively, with the ATLAS detector at the LHC. The measurement is reported in the centre-of-mass frame...
Article
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A search for the exclusive decays of the Higgs and Z bosons to a ϕ or ρ meson and a photon is performed with a pp collision data sample corresponding to an integrated luminosity of up to 35.6 fb−1 collected at s√=13 TeV with the ATLAS detector at the CERN Large Hadron Collider. These decays have been suggested as a probe of the Higgs boson coupling...
Article
Full-text available
A search for W′-boson production in the W′→tb¯→qq¯′bb¯ decay channel is presented using 36.1fb⁻¹ of 13 TeV proton–proton collision data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search is interpreted in terms of both a left-handed and a right-handed chiral W′ boson within the mass range 1–5 TeV. Identificati...
Article
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A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing hadronic jets and missing transverse momentum, but no electrons or muons, is presented. The data used in this search were recorded in 2015 and 2016 by the ATLAS experiment in s=13 TeV proton-proton collisions at the Large Hadron Collider,...
Article
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This paper presents a search for direct electroweak gaugino or gluino pair production with a chargino nearly mass-degenerate with a stable neutralino. It is based on an integrated luminosity of 36.1 fb−1 of pp collisions at \( \sqrt{s}=13 \) TeV collected by the ATLAS experiment at the LHC. The final state of interest is a disappearing track accomp...
Article
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The inclusive and fiducial \(t\bar{t}\) production cross-sections are measured in the lepton+jets channel using \(20.2~\hbox {fb}^{-1}\) of proton–proton collision data at a centre-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. Major systematic uncertainties due to the modelling of the jet energy scale and b-tagging efficiency...
Article
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A bstract A search for supersymmetry involving the pair production of gluinos decaying via third-generation squarks into the lightest neutralino $$ \left({\tilde{\chi}}_1^0\right) $$ χ ˜ 1 0 is reported. It uses LHC proton-proton collision data at a centre-of-mass energy $$ \sqrt{s}=13 $$ s = 13 TeV with an integrated luminosity of 36.1 fb ⁻¹ colle...
Article
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A direct search for the standard model Higgs boson decaying to a pair of charm quarks is presented. Associated production of the Higgs and Z bosons, in the decay mode ZH→ℓ+ℓ−cc¯ is studied. A data set with an integrated luminosity of 36.1 fb−1 of pp collisions at s=13TeV recorded by the ATLAS experiment at the LHC is used. The H→cc¯ signature is id...
Article
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A search is presented for photonic signatures, motivated by generalized models of gauge-mediated supersymmetry breaking. This search makes use of proton-proton collision data at s=13 TeV corresponding to an integrated luminosity of 36.1 fb−1 recorded by the ATLAS detector at the LHC, and it explores models dominated by both strong and electroweak p...
Article
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A search for the narrow structure, X(5568), reported by the D0 Collaboration in the decay sequence X→Bs0π±, Bs0→J/ψϕ, is presented. The analysis is based on a data sample recorded with the ATLAS detector at the LHC corresponding to 4.9 fb−1 of pp collisions at 7 TeV and 19.5 fb−1 at 8 TeV. No significant signal was found. Upper limits on the number...
Article
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This paper presents a measurement of the W boson production cross section and the W +/W − cross-section ratio, both in association with jets, in proton-proton collisions at \( \sqrt{s}=8 \) TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is performed in final states containing one electron and missing transverse momentum...
Article
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A search for the standard model Higgs boson produced in association with a top-quark pair, tt¯H, is presented. The analysis uses 36.1 fb−1 of pp collision data at s=13 TeV collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search targets the H→bb¯ decay mode. The selected events contain either one or two electrons...
Article
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A search for high-mass resonances decaying to τν using proton-proton collisions at s=13 TeV produced by the Large Hadron Collider is presented. Only τ-lepton decays with hadrons in the final state are considered. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 36.1 fb−1. No statistically significant exce...
Article
Full-text available
A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb−1 of proton–proton collision data at s=13TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state XH...
Article
Full-text available
A search for the associated production of the Higgs boson with a top quark pair (tt¯H) is reported. The search is performed in multilepton final states using a data set corresponding to an integrated luminosity of 36.1 fb−1 of proton-proton collision data recorded by the ATLAS experiment at a center-of-mass energy s=13 TeV at the Large Hadron Colli...
Article
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A search for heavy resonances decaying into a pair of \(Z\) bosons leading to \(\ell ^+\ell ^-\ell ^+\ell ^-\) and \(\ell ^+\ell ^-\nu \bar{\nu }\) final states, where \(\ell \) stands for either an electron or a muon, is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 \(\text {TeV}\) corresponding to an int...
Article
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This paper presents combinations of inclusive and differential measurements of the charge asymmetry (AC) in top quark pair \( \left(\mathrm{t}\overline{\mathrm{t}}\right) \) events with a lepton+jets signature by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. The data corres...
Article
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A search for long-lived, massive particles predicted by many theories beyond the Standard Model is presented. The search targets final states with large missing transverse momentum and at least one high-mass displaced vertex with five or more tracks, and uses 32.8 fb−1 of s=13 TeVpp collision data collected by the ATLAS detector at the LHC. The obs...
Article
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A search for electroweak production of supersymmetric particles in scenarios with compressed mass spectra in final states with two low-momentum leptons and missing transverse momentum is presented. This search uses proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2015–2016, corresponding to 36.1 fb−1 of in...
Article
Full-text available
A search for massive coloured resonances which are pair-produced and decay into two jets is presented. The analysis uses 36.7 fb−1 of √s = 13 TeV pp collision data recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the background prediction is observed. Results are interpreted in a SUSY simplified model wher...
Article
Full-text available
A search for doubly charged Higgs bosons with pairs of prompt, isolated, highly energetic leptons with the same electric charge is presented. The search uses a proton–proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to 36.1 fb−1 of integrated luminosity recorded in 2015 and 2016 by the ATLAS detector at the LHC. This...
Article
Full-text available
The differential cross-section for the production of a W boson in association with a top quark is measured for several particle-level observables. The measurements are performed using 36.1 fb - 1 of pp collision data collected with the ATLAS detector at the LHC in 2015 and 2016. Differential cross-sections are measured in a fiducial phase spac...
Article
Full-text available
This paper reports searches for heavy resonances decaying into ZZ or ZW using data from proton-proton collisions at a centre-of-mass energy of \( \sqrt{s}=13 \) TeV. The data, corresponding to an integrated luminosity of 36.1 fb−1, were recorded with the ATLAS detector in 2015 and 2016 at the Large Hadron Collider. The searches are performed in fin...
Article
Full-text available
A search for doubly charged Higgs bosons with pairs of prompt, isolated, highly energetic leptons with the same electric charge is presented. The search uses a proton–proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to 36.1 \(\text {fb}^{-1}\) of integrated luminosity recorded in 2015 and 2016 by the ATLAS detector at...
Article
Full-text available
A search is conducted for new resonances decaying into a W W or W Z boson pair, where one W boson decays leptonically and the other W or Z boson decays hadronically. It is based on proton-proton collision data with an integrated luminosity of 36.1 fb−1 collected with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of \( \...
Article
Full-text available
The production of a top quark in association with a Z boson is investigated. The proton–proton collision data collected by the ATLAS experiment at the LHC in 2015 and 2016 at a centre-of-mass energy of s=13TeV are used, corresponding to an integrated luminosity of 36.1fb−1. Events containing three identified leptons (electrons and/or muons) and two...
Article
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The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb⁻¹. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti-kt algorith...
Article
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The coupling properties of the Higgs boson are studied in the four-lepton (e, μ) decay channel using 36.1 fb−1 of pp collision data from the LHC at a centre-of-mass energy of 13 TeV collected by the ATLAS detector. Cross sections are measured for the main production modes in several exclusive regions of the Higgs boson production phase space and ar...
Article
Full-text available
A search for massive coloured resonances which are pair-produced and decay into two jets is presented. The analysis uses 36.7 fb\(^{-1}\) of \(\sqrt{s}\) = 13 TeV pp collision data recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the background prediction is observed. Results are interpreted in a SUSY simp...
Article
Full-text available
A measurement of the production of three isolated photons in proton–proton collisions at a centre-of-mass energy s=8 TeV is reported. The results are based on an integrated luminosity of 20.2 fb −1 collected with the ATLAS detector at the LHC. The differential cross sections are measured as functions of the transverse energy of each photon, the dif...
Article
Full-text available
A search is conducted for new resonances decaying into a W or Z boson and a 125 GeV Higgs boson in the \( \nu \overline{\nu}b\overline{b} \), \( {\ell}^{\pm}\nu b\overline{b} \), and \( {\ell}^{+}{\ell}^{-}b\overline{b} \) final states, where ℓ± = e± or μ±, in pp collisions at \( \sqrt{s}=13 \) TeV. The data used correspond to a total integrated lu...
Article
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The modification of the production of J/ ψ, ψ(2 S) , and Υ(nS) (n= 1 , 2 , 3) in p+Pb collisions with respect to their production in pp collisions has been studied. The p+Pb and pp datasets used in this paper correspond to integrated luminosities of 28nb-1 and 25pb-1 respectively, collected in 2013 and 2015 by the ATLAS detector at the LHC, both at...
Article
A search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of 36.1 fb−1 , recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. No...
Article
This paper presents a direct measurement of the decay width of the top quark using tt¯ events in the lepton+jets final state. The data sample was collected by the ATLAS detector at the LHC in proton–proton collisions at a centre-of-mass energy of 8 TeV and corresponds to an integrated luminosity of 20.2 fb −1 . The decay width of the top quark is m...
Article
Full-text available
A detailed study of multiparticle azimuthal correlations is presented using pp data at s=5.02 and 13 TeV, and p+Pb data at sNN=5.02 TeV, recorded with the ATLAS detector at the CERN Large Hadron Collider. The azimuthal correlations are probed using four-particle cumulants cn{4} and flow coefficients vn{4}=(−cn{4})1/4 for n=2 and 3, with the goal of...
Article
Full-text available
Measurements of ZZ production in the ℓ+ℓ−ℓ′+ℓ′− channel in proton–proton collisions at 13 TeV center-of-mass energy at the Large Hadron Collider are presented. The data correspond to 36.1 fb−1 of collisions collected by the ATLAS experiment in 2015 and 2016. Here ℓ and ℓ′ stand for electrons or muons. Integrated and differential ZZ→ℓ+ℓ−ℓ′+ℓ′− cross...
Article
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A search is presented for the direct pair production of the stop, the supersymmetric partner of the top quark, that decays through an R-parity-violating coupling to a final state with two leptons and two jets, at least one of which is identified as a b-jet. The data set corresponds to an integrated luminosity of 36.1 fb−1 of proton-proton collision...
Article
A measurement of the mass of the W boson is presented based on proton–proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb−14.6 fb−1 of integrated luminosity. The selected data sample consists of 7.8×1067.8×106 candidates in the W→μνW→μν channel and 5.9×1065.9×106...
Article
Full-text available
A search is performed for new phenomena in events having a photon with high transverse momentum and a jet collected in 36.7 fb−1 of proton–proton collisions at a centre-of-mass energy of s√ = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The invariant mass distribution of the leading photon and jet is examined to look for th...
Article
Full-text available
A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb⁻¹ of proton–proton collision data at s=13TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state XH...
Article
Full-text available
A search is performed for new phenomena in events having a photon with high transverse momentum and a jet collected in 36.7 fb - 1 of proton-proton collisions at a centre-of-mass energy of s = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The invariant mass distribution of the leading photon and jet is examined to lo...
Article
Full-text available
A measurement of the mass of the W boson is presented based on proton–proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to \(4.6~\hbox {fb}^{-1}\) of integrated luminosity. The selected data sample consists of \(7.8\times 10^6\) candidates in the \(W\rightarrow \mu \nu \...
Article
Full-text available
This paper presents a direct measurement of the decay width of the top quark using \(t\bar{t}\) events in the lepton+jets final state. The data sample was collected by the ATLAS detector at the LHC in proton–proton collisions at a centre-of-mass energy of 8 TeV and corresponds to an integrated luminosity of 20.2 fb\(^{-1}\). The decay width of the...
Article
Full-text available
Measurements of longitudinal flow correlations are presented for charged particles in the pseudorapidity range \(|\eta |<2.4\) using 7 and 470 \(\upmu \hbox {b}^{-1}\) of Pb+Pb collisions at \(\sqrt{s_{\text {NN}}}=2.76\) and 5.02 TeV, respectively, recorded by the ATLAS detector at the LHC. It is found that the correlation between the harmonic flo...
Article
Full-text available
A search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of 36.1 fb - 1 , recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 Te...
Article
Full-text available
The inclusive cross-section for the associated production of a W boson and top quark is measured using data from proton-proton collisions at \( \sqrt{s}=13 \) TeV. The dataset corresponds to an integrated luminosity of 3.2 fb−1, and was collected in 2015 by the ATLAS detector at the Large Hadron Collider at CERN. Events are selected requiring two o...
Article
Full-text available
A search for heavy neutral Higgs bosons and Z′ bosons is performed using a data sample corresponding to an integrated luminosity of 36.1 fb−1 from proton-proton collisions at \( \sqrt{s}=13 \) TeV recorded by the ATLAS detector at the LHC during 2015 and 2016. The heavy resonance is assumed to decay to τ +τ − with at least one tau lepton decaying t...
Article
Full-text available
A search for weakly interacting massive dark-matter particles produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and missing transverse momentum are considered. The analysis uses 36.1fb−136.1fb−1 of proton–proton collision data recorded by the ATLAS experiment at s√=13s=13 TeV in 2015 and...
Article
Full-text available
A search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a leptonically decaying Z boson in proton–proton collisions at s=13 TeV is presented. This search uses 36.1 fb −1 of data collected by the ATLAS experiment at the Large Hadron Collider. No significant deviation from the expectation of the Standard...
Article
Full-text available
A search for weakly interacting massive dark-matter particles produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and missing transverse momentum are considered. The analysis uses \(36.1 \; \mathrm {fb}^{-1}\) of proton–proton collision data recorded by the ATLAS experiment at \(\sqrt{s}=1...
Article
Full-text available
A search for neutral heavy resonances is performed in the \(WW\rightarrow e\nu \mu \nu \) decay channel using pp collision data corresponding to an integrated luminosity of \(36.1\,\hbox {fb}^{-1}\), collected at a centre-of-mass energy of 13\(\,\text {TeV}\) by the ATLAS detector at the Large Hadron Collider. No evidence of such heavy resonances i...
Article
Full-text available
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of 36.1 fb−1 at a centre-of-mass energy of 13 TeV collected in 2015 and 2016 with the ATLAS detector at the Large Hadron Collider. Even...