Testing nuclear coalescence with nuclei-antinucleon / antinuclei-nucleon balance measurements at the Large Hadron Collider

Description du projet

Étudier les mécanismes de formation des noyaux de matière et d’antimatière

Les scientifiques du Grand collisionneur de hadrons étudient la formation des anti-noyaux (les contreparties antimatière des noyaux atomiques) lors des collisions à haute énergie. Ces collisions créent un environnement extrêmement chaud et dense au sein duquel les noyaux fragiles, tels que les deutérons, ne devraient pas survivre. Avec le soutien du programme Actions Marie Skłodowska-Curie, le projet Nuclei Balance va étudiera comment les deutérons et les anti-noyaux sont produits, et si leur formation suit le même processus que les protons libres. Les chercheurs évalueront comment les propriétés quantiques, telles que le nombre de baryons, sont équilibrées entre les particules lors des collisions proton-proton. En utilisant les données du détecteur ALICE amélioré, la recherche fournira des informations précises et comparera les résultats avec les prédictions du modèle PYTHIA8.

Objectif

A hot topic at the Large Hadron Collider (LHC) is the production of anti-nuclei. In ultra high-energy collisions at the LHC, nuclei with very low binding energies are not expected to survive the dense and hot final state environment. This project aims to investigate the nuclei and anti-nuclei production in relativistic hadronic collisions at the LHC to test the microscopic mechanism of their production, which is still under debate. In particular, this project would focus on the first experimental measurement of how quantum numbers (in particular baryon number) of produced deuterons are balanced by other hadrons in proton-proton (pp) collisions. One can in this way experimentally test the coalescence hypothesis of nuclei production, directly by measuring if the proton in the deuteron is balanced by an antiproton exactly the same way as for a free proton. If this is the case, then it indicates that the proton in the deuteron is formed in the same way as a free proton. The idea to perform these measurements is presented in this proposal for the first time and has never been performed before. The same measurements can also be compared with the predictions from the famous PYTHIA8 model whose development and maintenance are centered around the Lund University Theory group. The balance is expected to depend on transverse momentum and could depend on multiplicity as this controls the number of final state interactions. To make the highest precision differential measurements, the analysis will use 13.6 TeV pp collision datasets to be taken in Run 3 (2022-2025) with the recently upgraded ALICE detector that can handle rates that are 10-100 times larger than before the upgrade. The ability to perform the measurements takes advantage of the expertise of the fellow and the supervisor who both have a long association with ALICE collaboration at the LHC and has the necessary expertise and network to carry out the measurements.