General information
Organisation
The French Alternative Energies and Atomic Energy Commission (CEA) is a key player in research, development and innovation in four main areas :
• defence and security,
• nuclear energy (fission and fusion),
• technological research for industry,
• fundamental research in the physical sciences and life sciences.
Drawing on its widely acknowledged expertise, and thanks to its 16000 technicians, engineers, researchers and staff, the CEA actively participates in collaborative projects with a large number of academic and industrial partners.
The CEA is established in ten centers spread throughout France
Reference
SL-DRF-24-0374
Direction
DRF
Thesis topic details
Category
Corpuscular physics and outer space
Thesis topics
The natural width of the Higgs boson in the diphoton channel
Contract
Thèse
Job description
The Higgs boson discovered at the LHC in 2012 is the cornerstone of the Standard Model (SM). Its properties, such as its mass or spin, are now better and better known. Nevertheless, the total width of the Higgs boson remains a fundamental parameter that is very difficult to measure at the LHC without the support of theoretical assumptions.
In this PhD thesis, we propose to pursue an original approach to measure this parameter, approach only possible in the diphoton decay channel of the Higgs boson. Indeed, in this channel the position of the mass peak depends on the interference between the Higgs boson signal and the background noise. The resulting shift depends on the natural width of the Higgs boson. This is a very small effect in the SM but could be larger when considering Higgs bosons produced at high transverse momentum.
This type of analysis requires a thorough mastery of the various uncertainties related to the experimental apparatus, in particular to the electromagnetic calorimeter (ECAL), and to the reconstruction of the electromagnetic objects. In order to improve the latter, the student will develop a new approach to electromagnetic-object reconstruction based on a technique initiated at CEA-Irfu by the CMS group and using state-of-the-art methods in artificial intelligence (Convolutional NN and Graph NN).
These two aspects will be addressed in parallel during the thesis. The student will be supervised by the CMS group of Irfu whose expertise in the ECAL and in the two-photon Higgs boson decay channel is internationally recognised.
University / doctoral school
PHENIICS (PHENIICS)
Paris-Saclay
Thesis topic location
Site
Saclay
Requester
Position start date
01/10/2023
Person to be contacted by the applicant
COUDERC Fabrice fabrice.couderc@cea.fr
CEA
DRF/IRFU/DPHP
CEA-Saclay Irfu/SPP
01 69 08 86 83
Tutor / Responsible thesis director
COUDERC Fabrice fabrice.couderc@cea.fr
CEA
DRF/IRFU/DPHP
CEA-Saclay Irfu/SPP
01 69 08 86 83
En savoir plus
https://irfu.cea.fr/Phocea/Vie_des_labos/Ast/ast_groupe.php?id_groupe=3425
https://cms.cern