Flavor, higgses, and CP violation
- Autores: Carlos Miro Arenas
- Directores de la Tesis: Francisco J. Botella (dir. tes.), Miguel Nebot Gómez (codir. tes.)
- Lectura: En la Universitat de València ( España ) en 2025
- Idioma: inglés
- Número de páginas: 252
- Tribunal Calificador de la Tesis: Maria Margarida Nesbitt Rebelo (presid.), Martín González-Alonso (secret.), M. Belén Gavela (voc.)
- Programa de doctorado: Programa de Doctorado en Física por la Universitat de València (Estudi General)
- Calificación: Sobresaliente Cum Laude
- Materias:
- Enlaces
- Resumen
This thesis investigates the flavor and scalar sectors, as well as possible sources of Charge-Parity (CP) violation, within different New Physics (NP) extensions beyond the Standard Model (SM). The work presented here is structured around four research articles, whose main goals are outlined below. In chapter 4, we analyze the most general Effective Field Theories (EFTs) that can be constructed from a spurion analysis, that is, with non-dynamical fields that are independent of the space-time coordinates. As a case example, one can consider the Minimal Flavor Violation (MFV) paradigm, which assumes that the only source of flavor symmetry breaking at low energies, both in the SM and in NP models, are the Yukawa couplings. Using the Hilbert series technology, we establish a clear criterion, formulated as a Saturation Theorem, to determine the most general effective theory that can be constructed in this setting. We then focus on the study of specific NP models, in particular, extensions of the scalar sector based on the SM gauge group that involve multiple Higgs doublets. On the one hand, in chapter 5, we analyze the connection between the mass spectrum of models that preserve CP invariance at the Lagrangian level in the scalar sector, and the CP properties of the vacuum. We find that, for any number of Higgs doublets, the mass spectrum of the new scalars contains at least one charged state and two neutral states whose masses cannot be much larger than the electroweak scale, once perturbativity requirements are imposed on the quartic couplings of the potential. Later on, chapter 6 resumes the question of spontaneous CP violation, but this time in the context of two-Higgs-doublet models where flavor conservation is imposed. Specifically, we examine the phenomenological implications of the simultaneous requirement of: (i) spontaneous CP breaking, (ii) the absence of scalar flavor-changing neutral currents, and (iii) the generation of a CP-violating fermion mixing matrix, in agreement with experimental data. In the lepton sector, these three conditions lead to a mixing matrix that exhibits mu-tau symmetry. Finally, in chapter 7, we attempt to quantify how large CP violation in B meson mixing can be within different NP scenarios. This analysis is motivated by the direct connection with the primordial baryon asymmetry in the B-mesogenesis mechanism. Among the NP scenarios considered, we focus on: (i) generic heavy NP in the mass mixing, (ii) extensions of the fermion sector with vector-like quark singlets that induce unitarity deviations in the Cabibbo-Kobayashi-Maskawa (CKM) matrix, and (iii) modifications of decay width mixing. Our analysis shows that future searches for CP violation in B meson mixing, both at LHCb and Belle II, will not be able to probe new regions of the parameter space in the most generic models. Moreover, the B-mesogenesis mechanism is in tension due to the overall difficulty of generating significant CP violation in B meson mixing beyond the SM. Before going into the details of our research, the first three chapters of this thesis provide a self-contained theoretical introduction to the different frameworks of interest for subsequent chapters. First, chapter 1 reviews the basic ingredients of the SM, with special emphasis on its flavor structure and the origin of CP violation within the CKM paradigm. In chapter 2, we introduce the technical aspects of Hilbert series, together with a selected set of mathematical results relevant to our analysis, such as the Molien-Weyl formula and a theorem by Brion. The main features of multi-Higgs-doublet models and, in particular, two-Higgs-doublet models are discussed in chapter 3. Special effort has been devoted to the preparation of several appendices that include detailed calculations and complementary explanations omitted from the main text. In particular, appendix A contains a user guide for our Mathematica notebook HilbCalc, which allows for the automated computation of Hilbert series restricted to classical Lie groups. Appendices B, C, and D present the details of the unitary bidiagonalization procedure, the diagonalization of orthogonal matrices O(3,R), and the renormalization group evolution of Yukawa matrices, respectively, which are relevant for chapter 6. Finally, appendices E and F contain detailed calculations of the one-loop scalar contributions to lepton dipole moments, and of the different contributions to B meson mixing in the models discussed in chapter 7.
