Experimental study of the antideuteron source in p-p collisions at LHC energies.

This thesis presents a first analysis of the correlation function for (anti)proton and (anti)deuteron based on a sample of pp collisions data collected in 2022 at √s = 13.6 TeV by the ALICE experiment at CERN. The study of momentum correlations among particles is employed in constraining light antinuclei formation mechanisms and validating models of coalescence of antinucleons into light antinuclei. This is motivated by the fact that a deeper understanding of the origin of cosmic light antinuclei opens the possibility of searching for them as indirect dark matter signals, having the capability to predict the expected signal and background rates. In this work, the femtoscopy technique is applied to measure the correlation functions for proton−proton (p−p) and proton−deuteron (p−d) pairs. The obtained p−p correlation is fitted with the Argonne ν18 plus the Coulomb potentials to extract a preliminary measurement of the proton source radius in minimum bias pp collisions, resulting equal to r = 1.069 ± 0.014 fm. The obtained p−d correlation function is discussed in comparison with the measurement in pp collisions at √s = 13 TeV. The analysis is based on a new framework developed to meet the goals of this thesis. The optimization of the particle identification selection criteria and the pair-building procedure is achieved in this work. The promising result motivates the extensions of the analysis to the complete pp dataset available from the ongoing LHC Run 3.