Measurement of D Meson Production. Probing QCD and LFV τ decay with the ATLAS detector

Abstract
The Standard Model, the prevailing theory in particle physics, successfully explains three of the four fundamental forces but has notable limitations. For instance, while it includes neutrinos, it does not account for their observed masses or the force of gravity. Additionally, although it provides accurate predictions, the complexity of calculations required for precise particle production modeling at accelerators can be challenging. This thesis investigates the Ds meson, a particle abundantly produced in accelerators, to study quark production and search for lepton-flavor violations. By analyzing collision data from the ATLAS detector at CERN, the thesis presents differential measurements of Ds meson production, including the previously unexplored high-momentum region. These results are compared to state-of-the-art theoretical predictions to provide valuable feedback to theory. The implications of these findings for improving searches for lepton-flavor-violating tau lepton decays, which are rare processes beyond Standard Model predictions, are also discussed.