CERN Accelerating science

This thesis focuses on three main research topics. First, it investigates the space-time properties and production mechanism of light nuclei in relativistic heavy ion collisions where quark-gluon plasma is present. Second, it studies the dynamics and interaction of simple hadrons with composite objects (deuterons). Third, it measures the scattering parameters of the strong interaction between the lightest strange meson and single and bound nucleons. The method used in this thesis to investigate the aforementioned topics is known as femtoscopy, which examines two-particle correlations in momentum space. This work presents the momentum correlations measured with the ALICE detector in Pb--Pb collisions at a collision energy of $\sqrt{s_{\rm NN}}$ = 5.02 TeV. It focuses on the measurement and interpretation of femtoscopic correlations between various particle pairs, including pions and deuterons, protons and deuterons, kaons and protons, and kaons and deuterons. All of these pairs can be adequately described by interactions involving both Coulomb and strong forces which are determined using various techniques such as resolving Schr$\ddot{o}$dinger equations, numerical parametrization, two- and three-body approaches, including higher order partial waves. The study determines the femtoscopic source sizes of non-identical two-particle pairs across different collision centralities. Notably, the pion$-$deuteron and proton$-$deuteron studies provide the first measurements of deuteron femtoscopic source sizes in Pb$-$Pb collisions. This measurement has not been previously possible in direct deuteron$-$deuteron studies due to insufficient data. As a result, this thesis offers unique values for the homogeneity lengths of composite objects. These values are further compared with those of simpler particles, such as pions and protons, to investigate their collective flow behavior, which is the driving force behind femtoscopic source dynamics. The proton$-$deuteron and kaon$-$proton studies provide the first experimental evidence of effects expected in large femtoscopic sources. Specifically, the proton$-$deuteron study indicates a reduced impact of three-body dynamics, as the data can be well described by both two- and three-body interactions involving the underlying nucleons of the pair. In contrast, the kaon$-$proton study demonstrates that, in heavy-ion collision sources, coupled channel effects play a negligible role in determining the correlation functions. Furthermore, the kaon$-$proton and kaon$-$deuteron studies present the first measurements of their scattering parameters using femtoscopic techniques. The measurement of the kaon$-$deuteron scattering length for the strong interaction is the first of its kind. This study opens the door to determining isospin-dependent parameters in the fundamental strangeness sector, which also enables insights into the kaon$-$neutron interaction—an interaction that is difficult to investigate experimentally due to the neutron's lack of charge. All the measured parameters are compared with expectations and previous measurements when available. This thesis provides also several insights into $m_{\rm{T}}$ scaling of non-identical particles and future directions in studies using the femtoscopy technique.