arXiv subjects

David Suarez

Publications and source records attributed to David Suarez.

6 recordsLinked to original sources

arXiv2026

Dark Matter as a Source for Lepton Flavor Violation

We will witness enormous progress in the experimental sensitivity to charged-lepton-violation processes in the near future. New physics signals of charged lepton violation might be around the corner without conflicting with existing astrophysical and accelerator bounds. In this work, we explore the possibility of having a dark matter particle as a source for $\mu\to e \gamma$, $\mu \to 3e$, and $\mu\to e$ conversion in nuclei. After computing the dark matter relic density and dark matter-nucleon scattering cross section, we outline the region of parameter space where one can simultaneously accommodate a dark matter fermion in agreement with existing collider and direct detection bounds, and positive signals in charged lepton violation observables.

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arXiv2026

Two-Component Dark Matter in the Type-I 2HDM

We investigate a two-component dark matter scenario in the type-I two-Higgs-doublet model. The dark sector contains a real scalar $s$ and a Dirac fermion $\chi$, whose stability is ensured by a $Z_4$ symmetry together with kinematic conditions. The scalar interacts with the visible sector through Higgs-portal couplings, while the fermion interacts with the scalar via Yukawa interactions. In this framework, we analyze the thermal freeze-out production of both candidates, accounting for annihilation, conversion, and semi-annihilation processes. A comprehensive scan over the multidimensional parameter space is performed in terms of physical masses, mixing angles, and portal couplings, imposing theoretical requirements such as perturbativity and vacuum stability. We confront the model with current experimental constraints, including the observed relic abundance, invisible Higgs decays, direct detection limits on spin-independent scattering cross sections, and electroweak precision observables. We find that viable regions of parameter space can satisfy all dark matter constraints, but collider bounds strongly constrain the scalar sector, narrowing the allowed regions and creating tension with those favored by dark matter phenomenology, particularly in the sub-TeV mass regime.

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arXiv2025

Type I + II Seesaw Model in light of the New Neutrino Oscillation Measurements

Global analysis of neutrino oscillation data slightly favors normal mass ordering. In this work, we investigate an extended scalar sector that naturally gives rise to a type I + II seesaw mechanism after spontaneous symmetry breaking and explore the interplay between collider physics and lepton flavor violation, adopting normal ordering. In particular, we focus on the rare muon decays $\mu \rightarrow e \gamma$ and $\mu \rightarrow 3e$ and the same-sign dilepton searches at LHC, a canonical signature of a doubly charged scalar. We conclude that neither the precise value of the sum of the neutrino masses, taken from DESI data that favors $\sum m_\nu=0.07$~eV, nor alternative cosmological fits which prefer a more relaxed limit $\sum m_\nu=0.1$~eV, significantly changes the theoretical prediction for these rare decays. However, we observe an interesting interplay between collider physics and lepton flavor violation depending on the choices of the vacuum expectation value of the triplet scalar. In particular, we find that $\mu \rightarrow 3e$ is more constraining than $\mu \rightarrow e\gamma$, and the $\mu \rightarrow 3e$ decay can yield a lower mass limit of $3$~TeV on the doubly charged scalar, surpassing current LHC constraint.

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arXiv2024

Multi-component secluded WIMP dark matter and Dirac neutrino masses with an extra Abelian gauge symmetry

Scenarios for secluded WIMP dark matter models have been extensively studied in simplified versions. This paper shows a complete UV realization of a secluded WIMP dark matter model with an extra Abelian gauge symmetry that includes two-component dark matter candidates, where the dark matter conversion process plays a significant role in determining the relic density in the Universe. The model contains two new unstable mediators: a dark Higgs and a dark photon. It generates Dirac neutrino masses and can be tested in future direct detection experiments of dark matter. The model is also compatible with cosmological and theoretical constraints, including the branching ratio of Standard model particles into invisible, Big Bang nucleosynthesis restrictions, and the number of relativistic degrees of freedom in the early Universe, even without kinetic mixing.

hep-ph↗

arXiv2023

Singlet-doublet Dirac fermion dark matter from Peccei-Quinn symmetry

Weakly Interacting Massive Particles (WIMPs) and axions are arguably the most compelling dark matter (DM) candidates in the literature. Here, we consider a model where the PQ symmetry solves the strong CP problem, generates radiatively Dirac neutrino masses, and gives origin to multicomponent dark sector. Specifically, scotogenic Dirac neutrino masses arise at one-loop level. The lightest fermionic mediator acts as the second DM candidate due to a residual $Z_2$ symmetry resulting from the PQ symmetry breaking. The WIMP DM component resembles the well-known singlet-doublet fermion DM. While the lower WIMP dark mass region is usually excluded, our model reopens that portion of the parameter space (for DM masses below $\lesssim 100$ GeV). Therefore, we perform a phenomenological analysis that addresses the constraints from direct searches of DM, neutrino oscillation data, and charged lepton flavor violating (LFV) processes. The model can be tested in future facilities where DM annihilation into SM particles is searched for by neutrino telescopes.

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arXiv2021

Effective Dirac neutrino mass operator in the Standard Model with a local Abelian extension

We present 48 types of solutions to the anomaly cancellation conditions of local Abelian extensions of the Standard Model (SM) with right-handed singlet chiral fermions. At least two of them acquire effective light Dirac neutrino masses, while the others get heavy masses from the spontaneous symmetry breaking of the local Abelian symmetry, forming a dark sector with multi-component and multi-generational fermionic dark matter. The corresponding effective Dirac neutrino mass operator can be realized at tree-level or radiatively by introducing extra scalars, and in some cases after imposing extra scotogenic conditions. The Dirac Zee model with Dirac fermionic dark matter is presented as an example of model where the neutrino and dark matter phenomenology are basically independent of each other.

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