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Accueil du site > Formation > Thèses - Stages de M2

M2 Intership : Measurement of the electroweak diboson production in the W±Z channel with Run 2 and Run 3 data

The scattering of vector bosons (VBS), V V → V V with V = W/Z/γ, is a key process with which to probe the SU(2)L ×U(1)Y gauge symmetry of the electroweak (EW) theory that determines the self-couplings of the vector bosons. Rare and difficult to differentiate from its important background, it was only observed during the Run 2 of the LHC. This internship will be dedicated to the detailed study of this process, with an important focus on the differential cross section measurements that can be useful for the search of new physics in the context of Effective Field Theories. The analysis will be performed with the joint Run 2 and (partial) Run 3 dataset. The internship will be fully integrated to the current activities of the ATLAS LAPP Group dedicated to the Standard Model and most particularly the diboson production studies. It will require a regular presence at CERN, and could potentially evolve on a PhD thesis project.

The integrated luminosity of Run 3 will allow to carefully study this process and use it as a frame for the search of new physics that could generate additional contributions to quartic gauge couplings (QGC). Run 3 will also be a very important period for the preparation of the longitudinally polarized VBS, VL VL → VL VL, that consists on an indirect approach to the study of the EW symmetry breaking mechanism. This PhD will focus on the VBS channel having a final state including a W and a Z boson as well as two hadronic jets. The most important challenges to these studies are the high theoretical uncertainties related to the signal and the background coming from the non-electroweak WZ production, as well as the systematic uncertainty rising from the energy reconstruction of the hadronic jets. The PhD student will have a major contribution on the WZjj analysis with full data from Run 3, including the study of the theoretical modelling of the signal and the most important background in collaboration with theoretical physicists. Machine learning approaches will be essential on many items of the analysis, such as the signal isolation or the quark and gluons separation that could lead to a decrease of the background. Finally, this PhD foresees the interpretation of the results in the context of Effective Field Theories, where ML techniques start to be used and appear to be particularly promising. In addition, the PhD student will contribute to the upgrade of the ATLAS Liquid Argon Calorimeter in the context of the upcoming second phase of the LHC. The duration of the PhD thesis is three years. The geographical proximity of LAPP and CERN, about 50 km and 35’ drive, will allow a strong involvement both with the data taking and detector operation and with the participation in person to the working meetings of the ATLAS Standard Model Group. A period of several months of continuous presence at CERN is foreseen.

  • supervisor : Iro Koletsou
  • email :
  • Phone number : +33 4 50 09 17 49