From Dark Sectors to the Axion-Neutrino Connection

TL;DR

A tese propõe uma visão integrada de física além do SM, conectando neutrinos, matéria escura, CP e o problema CP forte por meio de setores escuros, SCPV e axions. A abordagem centra-se em frameworks unificados com alta testabilidade, incluindo o seesaw escuro com DM, SCPV via singletos complexos, modelos Nelson–Barr com soluções para o θ̄, axion frameworks com acoplamentos axião-fótons/fermiões e simetrias PQ sabor mínimas que ligam sabor, neutrinos e DM. Resultados-chave incluem o mecanismo dark-linear seesaw com geração radiativa de massas de neutrinos ligada a DM, cenários de leptogênese assistida por SCPV e IA de CKM complexa mediada por setores escuros, e a apresentação de axion models (PQWW/DFSZ/KSVZ) com implicações de detecção. O trabalho destaca previsões observáveis em cLFV, detecção direta de DM (WIMP) e experimentos de axions, oferecendo caminhos práticos para testar a coesão entre neutrinos, DM e CP em cosmologia e física de partículas. Em conjunto, a pesquisa ilumina como estruturas unificadas podem endereçar múltiplos problemas abertos da física fundamental, com impactos práticos para futuras buscas experimentais e desenvolvimento teórico.

Abstract

The Standard Model (SM) of particle physics provides a successful description of fundamental particles and their interactions but fails to explain phenomena such as neutrino oscillations, dark matter (DM), and the baryon asymmetry of the Universe. These clear signs of BSM physics motivate extensions introducing new particles and symmetries. Theoretical questions like the flavor puzzle and the strong CP problem further guide BSM frameworks. This thesis explores BSM scenarios based on two guiding principles: constructing unified frameworks that address multiple open problems in (astro)particle physics and cosmology, and emphasizing their experimental testability through detailed phenomenological analyses. This approach uncovers deep connections between seemingly disconnected sectors, offering a more complete view of fundamental physics. We investigate dark sector models for the origin of neutrino masses, proposing a novel setup: dark linear seesaw, which radiatively links neutrino mass generation to DM candidates and predicts charged lepton flavor violation. In these scenarios, dark sector particles can constitute WIMP DM, testable via direct detection experiments. We study spontaneous CP violation induced by a complex scalar singlet, acting as a common origin of low- and high-energy CP violating effects relevant for leptogenesis. We also analyze a Nelson-Barr model that solves the strong CP problem, generates a realistic CKM matrix radiatively, and yields scalar WIMP DM. Additionally, we present unified axion frameworks in which a colored sector radiatively generates neutrino masses. These models predict distinctive axion couplings to photons and fermions and accommodate axion DM in both pre- and post-inflationary cosmologies. Finally, we explore minimal flavored Peccei-Quinn symmetries that link the flavor puzzle, neutrino masses and DM within a predictive and testable framework.

Figures (43)

• Figure 1: Allowed $m_{\beta \beta}$ regions as a function of $\alpha$ for the case where the lightest neutrino is massless obtained using Eqs. \ref{['eq:NOIOmbb1min']} and \ref{['eq:NOIOmbb2min']} and varying low-energy neutrino observables within their allowed 1$\sigma$ and 3$\sigma$ intervals by neutrino oscillation data presented in Table \ref{['tab:leptondata']} (see also Ref. deSalas:2020pgw). Results for NO (IO) are shown in red (blue). Current most constraining $0_\nu \beta \beta$ experimental upper-bound ranges are represented by vertical colored bars while future sensitivities are indicated in gray -- see Table \ref{['tab:dataNDBD']}.
• Figure 2: Evolution of a WIMP DM candidate yield $Y$ in terms of $m/T$ (see text for details). We set $m=100$ GeV and present three distinct $\langle \sigma v\rangle$ cases via colored contours. The dashed black horizontal line indicates the value of $Y$ leading to $\Omega h^2 = 0.12$ [see Eq. \ref{['eq:Oh2PlanckOG']}] and the equilibrium yield $Y_{\text{eq}}$ [see Eq. \ref{['eq:Yeq']}] is shown via a dashed gray contour.
• Figure 4: From left to right: diagramatic representation of the type I, II and III seesaw interactions, mediated by a singlet fermion $\nu_R$, scalar triplet $\Delta$ and fermionic triplet $\Sigma_{R}$, respectively.
• Figure 5: One-loop scotogenic neutrino mass diagram in the weak-basis (mass-basis) on the left (right).
• Figure 6: Lowest order one-loop diagrams for neutrino mass generation: dark-seeded LSS (left) and additional correction to the bare heavy neutrino mass (right) (see text for details).