New Physics Hints from Flavour

Abstract

This Thesis presents my personal contributions to two distinct fields, namely the recent experimental anomalies in B-meson decays, and the longstanding quest for a theoretical explanation of lepton masses and mixings, under a unifying umbrella: Flavour Physics. The modern view of the Standard Model as an effective theory is motivated, and the dual role of flavour, as a probe of New Physics effects on one side, and as a piece of the puzzle itself on the other, is emphasized. By jointly discussing two physics cases of different nature, I attempt to offer a broader perspective on the current status of Beyond Standard Model searches. The discussion begins with a preliminary review of Standard Model Effective Field Theories, in which some utility results in theory matching are presented. The focus then moves to B-meson decay anomalies: after introducing Lepton Flavour Universality, we discuss the phenomenology of a specific Standard Model extension by scalar leptoquarks, and also present the Effective Field Theory framework of Rank-One Flavor Violation, providing a less detailed but broader picture for the case of neutral-current anomalies. Finally, we tackle the Standard Model flavour puzzle, describing an attempt to address charged lepton mass hierarchies in the framework of supersymmetric modular invariant models of lepton flavour.

PhD Thesis

References in corpus (14)

• B-physics anomalies: a guide to combined explanations
• Measurement of the branching ratio of ${\bar{B}}^0\to D^{\ast +}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with a semileptonic tagging method
• Confronting lepton flavor universality violation in B decays with high-$p_T$ tau lepton searches at LHC
• Simultaneous Explanation of the $R_K$ and $R(D^{(\ast )})$ Puzzles
• Lepton Flavor Violation in B Decays?
• Gauge leptoquark as the origin of B-physics anomalies
• Unification and Fermion Mass Structure
• The role of the $S_3$ GUT leptoquark in flavor universality and collider searches
• KL to pi0 e+ e- and KL to pi0 mu+ mu- : A binary star on the stage of flavor physics
• Improved Bhabha cross section at LEP and the number of light neutrino species
• $B$ decay anomalies and dark matter from vectorlike confinement
• A search for the decay modes B+/- to h+/- tau l
• Flavour from accidental symmetries
• Improved limit on the branching fraction of the rare decay $K_S^0\to {\mu }^{+}{\mu }^{-}$