Exploring Freeze-out and Freeze-in Dark Matter via Effective Froggatt-Nielsen Theory

TL;DR

This paper investigates a Froggatt-Nielsen based extension of the Standard Model, exploring how a flavon field mediates dark matter production via freeze-out and freeze-in, and analyzing its implications for neutrino masses and experimental detection.

Contribution

It introduces a minimal Froggatt-Nielsen framework that links dark matter genesis, neutrino mass generation, and testable flavor-changing processes.

Findings

Dark matter can be produced through freeze-out and freeze-in mechanisms.

The model predicts detectable signals in future direct detection experiments.

Flavor-changing processes constrain the parameter space.

Abstract

Motivated by the dynamical reasons for the hierarchical structure of the Yukawa sector of the Standard Model (SM), we consider an extension of the SM with a complex scalar field, known as `flavon', based on the Froggatt-Nielsen mechanism. In an effective theory approach, the SM fermion masses and mixing patterns are generated in orders of the parameter related to the vacuum expectation value of the flavon field and the cut-off of the effective theory. By introducing right-handed neutrinos, we study the viability of the lightest right-handed neutrino as a dark matter candidate, where the same flavon field acts as a mediator between the dark and the SM sectors. We find that dark matter genesis is achieved both through freeze-out and freeze-in mechanisms encompassing the $\mathcal{O}(\text{GeV})$ -- $\mathcal{O}(\text{TeV})$ mass range of the mediator and the dark matter particle. In addition to tree-level spin-dependent cross section, the model gives rise to tree- and loop-level contributions to spin-independent scattering cross section at the direct detection experiments such as XENON and LUX-ZEPLIN which can be probed in their future upgrades. By choosing suitable Froggatt-Nielsen charges for the fermions, we also generate the mass spectrum of the SM neutrinos via the Type-I seesaw mechanism. Flavor-changing neutral current processes, such as radiative lepton decay, meson mixing, and top-quark decay remain the most constraining channels and provide testability for this minimal setup that addresses several major shortcomings of the SM.