| RESEARCH TOPICS |
ATLAS
Collaboration
Since 2005, continuing |
Physics: early inclusive searches for Supersymmetry in decay cascades with missing transverse momentum and leptons in the final state. Early search for the Standard Model Higgs boson in the decay H→γγ. Some involvement in a 13 TeV search for ttH associated production in the multilepton channel. Determination of the absolute LHC luminosity using the van der Meer scan technique. Fast physics monitoring.
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ATLAS Spokesperson (since March 2021). |
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ATLAS Deputy Spokesperson (2017−2021). |
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ATLAS Physics Coordinator (2014−2015) and Deputy Physics Coordinator (2013−2014). |
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ATLAS Supersymmetry Working Group Co-convenor (2011−2013) |
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ATLAS Data Preparation Coordinator (2009−2010) and Deputy Data Preparation Coordinator (2006−2009). The ATLAS Data Preparation activity coordination includes responsibility for detector calibration and alignment, reconstruction of primary physics objects, prompt reconstruction and data reprocessing, detector simulation, magnetic field, data quality and software commissioning, data streaming, meta data, luminosity determination, event displays. |
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Software developments for high-level trigger steering and configuration (2005−2006). Co-development of ATLAS run-query toolkit (since 2008). |
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TMVA Project
Since 2006, continuing |
The Toolkit for Multivariate Analysis (TMVA) is a ROOT-based machine learning environment for the processing and parallel evaluation of multivariate classification techniques. TMVA is specifically designed to the needs of HEP applications, but is also employed in industry and finance. Founded the TMVA project, with currently six core members (CERN, Switzerland, Bonn and Heidelberg, Germany), and approximately 30 developers worldwide. |
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TMVA is a substantial package including more than ten different multivariate approaches. It has a broad user base in all HEP experiments. TMVA is developed and distributed as integral part of the ROOT analysis framework. |
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Gfitter Project
Since 2006, continuing |
Development of a generic fitting package for HEP model testing, embedded in the C++/ROOT framework. Founded Gfitter project group consisting of (as of now) eight core members from CERN and DESY. The project presently features via independent plugins full implementations of the global Standard Model fit at the electroweak scale, an extension of the Higgs sector to two doublets, Supersymmetry extensions, and oblique parameter predictions of several Higgs and extra dimensions models. |
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BABAR Collaboration
1997 − 2005 |
Work for Cherenkov particle identification detector (DIRC). Test and installation of front-end electronics boards. Contributions to calibration and monitoring software. Development of Cherenkov angle and photon timing fits. Responsibilities in detector operation and system management. |
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Physics analyses of rare B decays without charm: Measurement of CP violation in B→ρπ decays. Time-dependent Dalitz-plot analysis of B→3π decays and measurement of the CP-violating CKM angle α. Search for physics beyond the Standard Model in loop-induced (penguin) decays. Work on collaboration-wide analysis tools. Responsibilities for physics groups and reviews. Member of IN2P3 strategy group for the future of particle physics in France. |
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Member of Heavy Flavour Averaging Group (HFAG). Responsible for world averages of CP-violation measurements from B Factories and Tevatron experiments. |
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CKMfitter Project
1999 − 2007 |
Framework for the phenomenological interpretation of measurements related to the CKM matrix. Co-founder and leader of the CKMfitter group, which has collaborators from BABAR (physicists from France and Germany) and Belle (Japan and Hawaii). |
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The package includes treatments of CP violation in the kaon and B-meson sectors, the interpretation of measurements related to the unitarity triangle angles α, β and γ, neutral B(s)-meson oscillation, semileptonic, charmless hadronic, leptonic and radiative B decays, semileptonic and ultra-rare kaon decays. Emphasis is put on a careful statistical analysis. |
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Apart from Standard Model metrology, CKMfitter allows to perform fits to generic New Physics models contributing to the kaon and B-meson sectors. |
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Muon g−2 and α-QED(s)
Since 1996, continuing |
Evaluation of the hadronic vaccum polarisation contributions to muon anomalous magnetic moment and to the running of the QED coupling at the Z-boson mass. The phenomenoligical analysis uses low-energy hadronic spectral functions (cross sections) from electron-positron annihilation and tau decays to experimentally determine hadronic conntributions that cannot be computed with perturbative QCD. The hadronic contributions represent the main theoretical uncertainty in the Standard Model predictions of these observables. Excellent theoretical precision for g−2 is mandatory to confront it with the precise experimental value, with the aim to successfully detect or constrain physics beyond the Standard Model. Accurate knowledge of α(MZ) is crucial to constrain the mass of the Higgs boson via the global electroweak fit (see Gfitter project above), which drives the design of the search analyses at the LHC. All work on this topic is done in collaboration with Prof. Michel Davier (LAL-Orsay) and others. |
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Co-author of muon g−2 particle data group (PDG) review, and associated PDG member. |
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Test of conserved vector current (CVC) hypothesis by comparing tau vector spectral functions with isovector electron-positron annihilation data. Phenomenological fits to ρ lineshape and discovery of yet unresolved CVC discrepancy in two-pion channel. |
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Co-development of new unfolding approach based on Singular Value Decomposition. |
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QCD Phenomenology
Since 1996, continuing |
Determination of strong coupling constant from QCD fit to tau hadronic width and spectral moments. Experimental observation of running strong coupling between 1 GeV and tau mass. Study of perturbative QCD properties and determination of nonperturbative contributions at the tau mass scale and below. Study of chiral symmetry and QCD sum rules in vector minus axial-vector currents. |
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ALEPH Collaboration
1994 − 1997 Ph. D.
Again in 2002 |
Determination of vector and axial-vector tau hadronic spectral functions via the measurement of exclusive hadronic invariant mass spectra, normalised to their branching fractions. The spectral functions serve as input to a large number of phenomenological applications (see QCD phenomenology section above). |
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Determination of strange-quark mass and CKM matrix element |Vus| from QCD fits to tau spectral function with strangeness in final state. |
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Co-development of novel unfolding approach based on Singular Value Decomposition (1994). |
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OPAL Collaboration
1993 − 1994 Diploma |
Search for CP violation in Z decays to tau pairs, parametrised by a complex weak dipole moment originating from sources beyond the Standard Model. Development and use of optimal observables based on matrix elements. |