14 research outputs found

    EWK physics prospects for the HL-LHC

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    International audienceThe Large Hadron Collider (LHC) has been successfully delivering proton-proton collision data at the unprecedented center of mass energy of 13 TeV. An upgrade is planned to increase the instantaneous luminosity delivered by high luminosity LHC (HL-LHC), aiming to deliver a total of about 3000/fb of data to the ATLAS and CMS detectors. To cope with the expected data-taking conditions the ATLAS and CMS experiments are planning major upgrades of the detector. In this contribution we present an overview of the physics reach expected for electroweak measurements and searches at the HL-LHC for the CMS and ATLAS experiments. The prospects for high-precision measurements and study of rare processes are presented

    Calibration des cascades Ă©lectromagnĂ©tiques, application de l’apprentissage profond Ă  la reconstruction du recul hadronique et mesure de la distribution en impulsion transverse du boson W dans l’expĂ©rience ATLAS

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    The initial part of the thesis contains the description of the method for electromagnetic calorimeter calibration, correcting for the Data-MC discrepancy in the development of the electromagnetic showers in the calorimeter. The method improves electron identification and reduces the associated systematic uncertainty.The major part of the thesis is dedicated to the precise measurement of the W boson transverse spectrum using the data, collected by the ATLAS experiment at the energies of 5 and 13 TeV during two special low pile-up runs in 2017 and 2018. The motivation for the precise measurement of the W boson transverse spectrum is twofold. First, it serves as a test for the theoretical predictions obtained within the Standard Model and allows to benchmark the performance of the Monte-Carlo (MC) generators. The second reason is because the W pT spectrum is an input component for the measurement of the W boson mass which is a Standard Model parameter. The use of low pile-up data allows to significantly reduce the hadronic recoil systematic uncertainty improving the precision of the spectrum measurement. The thesis describes the methodology of the W boson pT spectrum measurement as well as the imposed calibrations, corrections and the associated uncertainties. The final result is obtained from the measured hadronic recoil using an unfolding procedure and is compared to the theoretical predictions obtained with different Monte-Carlo generators. An alternative method for the hadronic recoil reconstruction with the use of deep neural networks is proposed in the thesis. The method is shown to improve the resolution of the measured hadronic recoil by about 10% in the most relevant region of low pT. The observables obtained using approach improve the sensitivity to the mass of the W boson.La premiĂšre partie de la thĂšse contient une description de la mĂ©thode d'Ă©talonnage du calorimĂštre Ă©lectromagnĂ©tique, corrigeant les diffĂ©rences entre les donnĂ©es et la simulation pour ce qui concerne le dĂ©veloppement des cascades Ă©lectromagnĂ©tiques dans le calorimĂštre. La mĂ©thode amĂ©liore l'identification des Ă©lectrons et rĂ©duit l'incertitude systĂ©matique associĂ©e. La majeure partie de la thĂšse est consacrĂ©e Ă  la mesure prĂ©cise du spectre en impulsion transverse (pT) du boson W Ă  l'aide des donnĂ©es collectĂ©es par l'expĂ©rience ATLAS Ă  des Ă©nergies dans le centre de masse de 5 et 13 TeV lors de deux prises de donnĂ©es spĂ©ciales, Ă  faible taux d’empilement, en 2017 et en 2018. La motivation pour la mesure prĂ©cise du spectre en impulsion transverse du boson W est double. PremiĂšrement, elle sert de test pour les prĂ©dictions thĂ©oriques obtenues dans le cadre du ModĂšle Standard et permet de comparer les performances des gĂ©nĂ©rateurs Monte-Carlo (MC). La deuxiĂšme raison est que ce spectre est un ingrĂ©dient Ă  la mesure de la masse du boson W, qui est un paramĂštre du ModĂšle Standard. L'utilisation de donnĂ©es Ă  faible taux d'empilement permet de rĂ©duire significativement l'incertitude systĂ©matique due au recul hadronique et amĂ©liore de ce fait la prĂ©cision sur la mesure du spectre. La thĂšse dĂ©crit la mĂ©thodologie de la mesure du spectre en pT du boson W ainsi que les Ă©talonnages appliquĂ©s, les corrections et les incertitudes associĂ©es. Le rĂ©sultat final est obtenu Ă  partir du recul hadronique mesurĂ© Ă  l'aide d'une procĂ©dure de dĂ©convolution des effets de dĂ©tecteur et est comparĂ© aux prĂ©dictions thĂ©oriques obtenues avec diffĂ©rents gĂ©nĂ©rateurs Monte-Carlo. Une mĂ©thode alternative pour la reconstruction du recul hadronique, avec l'utilisation de rĂ©seaux neuronaux profonds est proposĂ©e dans la thĂšse. Il y est montrĂ© que cette mĂ©thode amĂ©liore la rĂ©solution du recul hadronique mesurĂ© d'environ 10% dans la rĂ©gion la plus pertinente, de faible pT. Les observables obtenus par cette approche amĂ©liorent la sensibilitĂ© Ă  la masse du boson W
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