Experiments and phenomenology of electric dipole moments

Abstract

The Standard Model (SM) is the best description of fundamental particles and their interactions we have to date. From this theory, all phenomena in the macroscopic world (except for gravity) can be explained, and it has successfully predicted all outcomes of particle experiments on Earth. However, cosmological observations of the early Universe yield a large imbalance between its content of matter and antimatter, which is several orders of magnitude above the SM prediction. To explain these observations, new interactions that do not respect the charge-parity symmetry must exist beyond the SM. Such interactions would induce electric dipole moments (EDMs) in known particles. In Part I of this thesis, we propose to extend the active experimental program of EDM searches to charm and bottom baryons, $\tau$ leptons, and $\Lambda$ hyperons; also allowing the measurement of their corresponding magnetic dipole moments (MDMs). The EDM and MDM of short-lived particles can be accessed with a bent-crystal experiment to be installed in the Large Hadron Collider (LHC), while longer-lived $\Lambda$ particles can be measured at the LHCb experiment with no additional instrumentation. In Part II, an analysis of LHCb data to measure the $\Lambda$ polarization in $\Lambda_c^+ \to \Lambda \pi^+ \pi^+ \pi^-$ decays, essential ingredient for the proposed measurement, is presented. In the last part of the thesis, we derive new indirect bounds on heavy quark EDMs with already available data and explore the phenomenological implications of these and other EDM limits on New Physics models, with special emphasis on extensions of the SM with colour-octet scalars.