Description

The project aims to deepen our theoretical understanding of a deconfined state of matter, the quark–gluon plasma (QGP), produced in ultrarelativistic heavy-ion collisions. Because the QGP exists for only an extremely short time, it cannot be studied with external probes. Instead, we will use jets, collimated sprays of particles also created in these collisions, to explore the QGP’s dynamics.

The main goal is to understand how jets are modified by their interactions with the QGP compared to jets in proton-proton collisions, where no QGP is formed. In particular, the project will investigate how different aspects of QGP dynamics are imprinted in a novel class of observables called energy correlators. These observables have quickly become a hot topic in the field, attracting strong theoretical and experimental interest, because they provide a direct link between quantum field theory and measurements at the LHC.

Within this project, we will compute energy correlators in ultrarelativistic heavy-ion collisions using a novel approach that combines their formal properties, such as the light-ray operator product expansion, with perturbative QCD calculations of matrix elements. Methodologically, the work will involve analytical perturbative calculations of 1→2 and 1→3 QCD splittings in the presence of a background medium, as well as their numerical evaluation in order to obtain energy correlators. The project will also include the design and theoretical calculation of new energy correlator-based observables, tailored to probe specific phenomena such as medium anisotropies. Depending on the candidate’s progress and interests, the thesis can emphasize either formal theory or phenomenological applications.

This project provides the opportunity to work at the interface between high-energy theory and phenomenology, combining analytical calculations, numerical methods, with direct relevance to ongoing LHC experiments, in a rapidly evolving and exciting area of high-energy physics.

Compétences requises

Le ou la candidat·e doit être titulaire d’un M2 en physique et posséder une formation solide en théorie quantique des champs et en physique des particules, en particulier dans les techniques perturbatives en QCD. Une expérience en programmation est un plus. Le ou la candidat·e doit pouvoir travailler en anglais.

Bibliographie

[1] “Heavy Ion Collisions: The Big Picture, and the Big Questions’’, Wit Busza, Krishna Rajagopal, Wilke van der Schee, Ann. Rev. Nucl. Part. Sci. . 68 (2018) 339-376, arXiv: 1802.04801 [hep-ph]
[2] “Elements of QCD for hadron colliders’’, Gavin P. Salam, arXiv:1011.5131 [hep-ph]
[3] “Resolving the Scales of the Quark-Gluon Plasma with Energy Correlators’’, Carlota Andres, Fabio Dominguez Raghav Kunnawalkam Elayavalli, Jack Holguin, Cyrille Marquet, and Ian Moult, , Phys. Rev. Lett. 130 (2023) 26, 262301, arXiv: 2209.11236 [hep-ph]
[4] “Energy Correlators: A Journey From Theory to Experiment’’, Ian Moult, Hua Xing Zhu, arXiv: 2506.09119 [hep-ph]
[5] “Simple Scaling Laws for Energy Correlators in Nuclear Matter’’, Carlota Andres, Fabio Dominguez, Jack Holguin, Cyrille Marquet, and Ian Moult, arXiv: 2411.15298 [hep-ph]

Mots clés

Chromodynamique quantique (QCD), Jets, Collisions de noyaux ultra-relativistes, Plasma de quarks et gluons