The remarkable success of the Standard Model (SM) of particle physics lies in its comprehensive description of the dynamics governing the behaviour of microscopic constituents of our Universe, ultimately translated into the discovery of a Higgs boson-like particle at CERN. Despite its predictive power, several SM shortcomings suggest the existence of more complete theory, solving long-standing issues like Dark Matter, baryon-antibaryon asymmetry, and neutrino oscillations, currently unexplained within the framework. As a result, the SM could represent a sensible approximation valid in the low-energy limit below the energy scale of new phenomena. The lack of a New Physics (NP) observation in the high energy domain has broadened the interest of the scientific community, now turning to complementary approaches.
High precision measurements with heavy flavour decays represent the strategy of choice when looking for indirect effects of NP at high energy scales, contributing to SM processes. The research conducted in this PhD project follows this approach at first. In this manuscript, we present a sensitivity evaluation for NP in semileptonic Λb0→Λc+μ−νˉμ transitions, alongside its first angular analysis performed with data collected by the LHCb experiment during the Run 2 of the Large Hadron Collider (LHC). Furthermore, novel enhancements to the offline LHCb software framework intended for the new LHC conditions are discussed.
High energy neutrinos produced at the LHC present an unmatched opportunity to test unexplored regions of the SM where NP could manifest. We describe the observation of muon collider neutrinos with the SND@LHC experiment, paving the way for a new frontier for testing the SM.
Under the assumption of NP interacting feebly with the SM, experiments running with high intensity beams could have a privileged access portal to a wealth of hidden particles, potentially including dark matter. In this context, we discuss the sensitivity of the SHiP experimental proposal to light dark matter, focusing on the case of elastic scattering off electrons
