Partenaires
Menu
Rechercher
Navigation
Accueil > Thèses, Stages, Formation et Enseignement > Propositions de thèses antérieures > Propositions de thèses 2022 > Jet calibration, cross-section measurements and alpha_S extraction at ATLAS and at the Future Circular Collider at CERN (FCC-ee)
Jet calibration, cross-section measurements and alpha_S extraction at ATLAS and at the Future Circular Collider at CERN (FCC-ee)
Title: Jet calibration, cross-section measurements and alpha_S extraction at ATLAS and at the Future Circular Collider at CERN (FCC-ee)
Supervisor: Luc Poggioli
Co-supervisor: Bogdan Malaescu
Team: Masses and fondamental interactions; ATLAS et FCC groups
Description:
The evaluation of the strong coupling constant alpha_S and the test of its running as a function of the energy scale, as predicted by the renormalisation group equation in QCD (RGE), can be done using jet cross section measurements. We propose to perform such studies using data accumulated by ATLAS mainly during the Run 2 of the LHC, with a possible extension to also use data collected during Run 3 (foreseen to start in March 2022).
With the increase in the accumulated luminosity, allowing for small statistical uncertainties even in the case of multi-dimensional cross-section measurements, it becomes more and more important to also reduce the systematic uncertainties as much as possible. This will be achieved by performing an absolute jet in-situ calibration, where physics and detector effects are well factorised. Such method will allow to rely less on the use of Monte Carlo simulation (MC), compared to the current relative jet in-situ calibration that uses extensive comparisons between data and MC. Indeed, while the current relative in-situ calibration method applied to the jets in data uses MC for describing both detector and physics effects in various event topologies, the absolute calibration method will use MC for describing the physics effects while the determination of the detector response will be fully data-driven.
Methods for extracting alpha_S and testing its RGE will also be studied in the context of the design studies for the FCC-ee collider, and their impact on the detectors design. For this purpose, event topologies with a hard photon emitted from the initial state particles (ISR) and several jets in the final state will be considered. Ratios of cross-sections with different jet multiplicities in the final state will allow to reduce the impact of systematic uncertainties. The use of the ISR method will be facilitated by the high luminosity foreseen at the FCC-ee. This will allow for a good understanding of the systematic uncertainties, when performing measurements on a broad range of the energy of the final state particles, with the same detector and collider conditions. Studies to optimise the detector design in view of such measurements will be performed.
Both in ATLAS and at FCC-ee, these very high precision studies will allow to perform stringent tests of QCD, and to probe potential signals of new physics at the highest scales accessible in laboratory.
Possible trips: CERN
Contacts:
- Luc Poggioli, 33 (0)1 44 27 73 81
- Bogdan Malaescu, 33 (0)1 44 27 91 30
Documentations:
Also in this section :
- Mesure de l’évolution du taux d’expansion de l’univers par la combinaison des relevés de supernovae ZTF et Subaru
- Extending the search potential for axion-like particles decaying into two photons with the ATLAS detector at the LHC
- Préparation de l’expérience Hyper-Kamiokande - un observatoire unique pour des événements rares dans l’Univers
- Révéler le mystère des rayons cosmiques par la radio : modélisation et analyse de signaux radios détectés par GRAND
- Recherche de la diffusion élastique cohérente des neutrinos solaires par l’expérience de matière noire XENONnT
- Etalonnage des jets, mesures de sections efficaces et extraction d’alpha_S dans ATLAS et au Futur Collisionneur Circulaire au CERN (FCC-ee)
- Mesures des paramètres d’oscillations de neutrinos avec le détecteur proche upgradé de T2K
- Tester l’invariance de Lorentz avec les sources astrophysiques de haute énergie : l’aube d’une nouvelle ère
- Réseaux de neurones et apprentissage profond pour la détection et la reconstruction des rayons cosmiques dans le domaine radio
- Développement d’algorithmes de reconstruction de particules fondés sur l’intelligence artificielle
- Recherche de la diffusion élastique cohérente de neutrinos issus de supernovæ avec l’expérience XENONnT
