Description du sujet de thèse

The objective of the thesis is to extract the distributions of partons (quarks, antiquarks, gluons) within atomic nuclei (nuclear parton distribution function, nPDF), explicitly taking into account the mechanisms of fully coherent radiative energy losses (FCEL) induced by nuclear matter. Recently, new sets of nPDFs have been determined using the production of hadrons (inclusive charged hadrons, D mesons, charmonia states J/psi) in proton-lead (pPb) collisions at the CERN LHC collider. These new, highly precise data should significantly reduce the uncertainties of nPDFs. However, it is necessary to account for energy loss phenomena that affect the production of these particles, to avoid significant systematic biases in the value of the extracted nPDFs, particularly in the region of small momentum fraction where experimental data are scarce. The proposed work in this thesis is to calculate, using a perturbative approach in quantum chromodynamics, the effects of FCEL in the various processes relevant to the extraction of nPDFs. Using artificial intelligence techniques and machine learning, new-generation nPDF sets, reliable because they include energy loss effects for the first time, will be extracted and made freely available to the community.

Contexte de travail

The work program consists first of familiarizing oneself with the formalism of energy loss, on the one hand, and the approach of collinear factorization in perturbative quantum chromodynamics, on the other. Energy losses will then need to be calculated numerically in a systematic manner, taking care to optimize the execution speed of these calculations. These calculations will be integrated into global fit approaches to extract parton distribution functions (PDFs). Finally, new sets of PDFs in nuclei will be extracted and must be integrated into the LHAPDF program, which lists the PDF sets and makes them easy to use for the user. Scientific articles will also be written and submitted for publication to report these new results.

Contraintes et risques

No particular constraints or risks.
The candidate will have the following skills: :
- must hold a Master's degree (M2) in subatomic physics.
- A good level of English is required.
- Computer skills will be an asset (Python, C++, etc.)
- Good communication and writing skills in English
- Ability to work both independently and collaboratively in an international team environment.

Informations complémentaires

The candidate will have the following skills: :
- must hold a Master's degree (M2) in subatomic physics.
- A good level of English is required.
- Computer skills will be an asset (Python, C++, etc.)
- Good communication and writing skills in English
- Ability to work both independently and collaboratively in an international team environment.