arXiv subjects

Juan Marchant González

Publications and source records attributed to Juan Marchant González.

9 recordsLinked to original sources

arXiv2026

A novel two loop inverse seesaw model

We propose a Standard Model (SM) extension where neutrinos get masses through a two-loop inverse seesaw mechanism. This naturally explains the smallness of the neutrino masses and allows seesaw mediators to be at the TeV scale with testable phenomenology. The model adds two real singlet scalars and four electrically neutral leptons to the SM. The extension considers the existence of two global Abelian symmetries, a continuous $U(1)$ and a discrete $Z_3$. The latter, remains unbroken after spontaneous symmetry breaking and forbids tree-level and one-loop neutrino masses, and stabilizes the dark matter (DM) candidates. This setup accommodates neutrino-oscillation data, yields two pseudo-Dirac heavy pairs with small active-sterile mixing, and predicts an effective Majorana mass $m_{ee}$ in the $2.1$-$4.4$ meV range for normal ordering. Charged-lepton flavor violation is naturally suppressed yet testable: for a representative benchmark we obtain BR$(μ\to e γ)\simeq 1.6 \times 10^{-14}$, with correlated signals in $μ\to eee$ and $μ$-$e$ conversion within next-generation experimental reach. Altogether, the radiative origin of neutrino masses links low-energy flavor observables to collider signatures, delineating discovery targets for MEG II, Mu2e/COMET, and the HL-LHC and distinguishing this framework from conventional inverse- and radiative-seesaw models. Moreover, the $Z_3$ guarantees a stable DM candidate, either scalar ($ρ$) or fermionic ($Ω$). Then, here we analyze and identify the viable parameter space that is consistent with the observed DM relic abundance for both situations.

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arXiv2026

Dark matter and scalar sector in a novel two-loop scotogenic neutrino mass model

We propose an extended $3+1$ Higgs doublet model where the Standard Model (SM) gauge structure is enhanced by the discrete symmetry $Q_6 \times Z_2 \times Z_4$, and the fermion content is extended with right-handed Majorana neutrinos. The scalar sector, besides four $SU(2)$ doublets, incorporates multiple gauge-singlet scalars. In our model, the tiny active neutrino masses arise from a novel radiative seesaw mechanism at two-loop level and the leptonic mixing features the cobimaximal mixing pattern compatible with neutrino oscillation experimental data. Along with this, the proposed model is consistent with SM quark masses and mixings as well as with the constraints arising from dark matter relic density and dark matter direct detection. Our analysis reveals that the best-fit point satisfying dark matter constraints yields a non-SM scalar with mass near $95$ GeV, which could be a possible candidate for the observed $95$ GeV diphoton excess. We further obtain other non SM scalars with masses at the subTeV scale which are within the LHC reach, while successfully complying with the experimental bounds arising from collider searches.

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arXiv2024

Phenomenological Aspects of Models with Low Scale Seesaw

Various phenomenological consequences of seesaw theories for the generation of the fermion mass hierarchy of the Standard Model have been analyzed, with an emphasis on models in which the light-active neutrino masses are derived from low-scale seesaw mechanisms. In particular, fermion masses and lepton flavor-violating decay processes, the flavor-changing neutral current, have been studied, and the implications of these theories for the observed dark matter relic density in the Universe have been determined. From the analysis of these phenomenological aspects, it was possible to determine the allowed parameter spaces of these theories and to obtain a parameter fit consistent with the currently measured experimental values. In this way, correlations between the different observables of the fermionic sector could be obtained, where all values were within the experimental ranges at $3σ$. Predictions for new physics consistent with cosmological limits were also obtained.

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arXiv2024

Phenomenology of extended multiHiggs doublet models with $S_4$ family symmetry

We propose extended 3HDM and 4HDM models where the SM gauge symmetry is enlarged by the spontaneously broken $S_4$ group, the preserved $Z_2$ and broken $Z_4$ cyclic symmetries. Each model has three active $SU(2)$ scalar doublets, in addition, the first one has an extra inert scalar singlet, whereas the second model has an inert scalar doublet. Furthermore, each model has several extra gauge singlet scalars, which are triplets under $S_4$. Both models yield the same structure of the mass matrices for the fermion sector, where a radiative seesaw generates the tiny light active neutrinos masses at one-loop level, through the $S_4$ triplets. The presence of flavor changing neutral currents mediated by heavy scalars allowed us to study the $(K^0-\overline{K}^0)$ and $(B_{d,s}^0-\overline{B}_{d,s}^0)$ meson mixings, in the parameter space that currently satisfies the experimental constraints. On the other hand, due to the preserved $Z_2$ symmetry, our proposed models have stable scalar and fermionic dark matter candidates. Furthermore, these models are consistent with the current pattern of SM fermion masses and mixings, with the measured dark matter relic abundance and successfully accommodate the constraints arising from meson oscillations and oblique parameters. The extra scalars in our models provide radiative corrections to the oblique parameters, where due to the presence of the scalar inert doublet, renders the 4HDM less restrictive than the 3HDM one.

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arXiv2024

Fermion masses and mixings and $g-2$ muon anomaly in a $Q_6$ flavored 2HDM

We propose an extended 2HDM with $Q_6\times Z_4\times Z_2$ symmetry that can successfully accommodate the SM fermion mass and mixing hierarchy. The tiny masses of the active neutrinos are generated from a type-I seesaw mechanism mediated by very heavy right-handed Majorana neutrinos. The model gives a natural explanation of the charged lepton mass hierarchy. Besides that, the experimental values of the physical observables of the neutrino sector: the neutrino mass squared splittings, the leptonic mixing angles and the leptonic Dirac CP violating phase, are also successfully reproduced for both normal and inverted neutrino mass hierarchies. We find a feasible range of values for the leptonic Dirac CP phase to be in the ranges $δ_{CP}\in (305.90, 348.70)^\circ$ for normal ordering and $δ_{CP}\in (308.00, 348.00)^\circ$ for inverted ordering, which is consistent with the 3$σ$ experimentally allowed limits. The sum of neutrino masses is obtained as $\sum m_i \in (58.03, 60.51)$ meV for normal ordering and $\sum m_i\in (98.07, 101.40)$ meV for inverted ordering which are well consistent with all the recent limits. In addition, the obtained ranges for the effective neutrino masses are $\langle m_{ee}\rangle \in (3.80, 4.38)$\, meV, $m_β \in (8.53, 9.34)\, \mbox{meV}$ for normal ordering and $\langle m_{ee}\rangle \in (47.85, 49.58) $ meV, $m_β \in (48.39, 50.09)\, \mbox{meV}$ for inverted ordering which are in agreement with the recent experimental bounds. For the quark sector, the derived results are also in agreement with the recent data on the quark masses and mixing angles. The model under consideration can also accommodate the muon anomalous magnetic moment.

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arXiv2024

Phenomenological aspects of the fermion and scalar sectors of a $S_4$ flavored 3-3-1 model

We proposed a viable and predictive model based on the $SU(3)_C \times SU(3)_L \times U(1)_X$ gauge symmetry, supplemented by the global $U(1)_{Lg}$ symmetry, the $S_4$ family symmetry and several auxiliary cyclic symmetries, which successfully reproduces the experimentally observed SM fermion mass and mixing pattern. The tiny active neutrino masses are generated through an inverse seesaw mechanism mediated by right-handed Majorana neutrinos. The model is consistent with the SM fermion masses and mixings and successfully accommodates the current Higgs diphoton decay rate constraints as well as the constraints arising from oblique $S$, $T$ and $U$ parameters and we studied the meson mixing due to flavor changing neutral currents mediated by heavy scalars, finding parameter space consistent with experimental constraints.

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arXiv2024

Predictive linear seesaw model with $Δ\left( 27\right) $ family symmetry

We consider a model that accounts for the smallness of neutrino masses through the linear seesaw mechanism and employs a $Δ(27)$ family symmetry to address the flavour problem. The model is predictive in the leptonic sector and faces constraints from Lepton Flavour Violation processes, namely $μ\to e γ$, which indicate a range for the Right-Handed neutrino mass.

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arXiv2024

Dark Matter from a Radiative Inverse Seesaw Majoron Model

We propose a Majoron-like extension of the Standard Model with an extra global $U(1)_X$-symmetry where neutrino masses are generated through an inverse seesaw mechanism at the 1-loop level. In contrast to the tree-level inverse seesaw, our framework contains dark matter (DM) candidates stabilized by a residual $\mathcal{Z}_2$-symmetry surviving spontaneous breaking of the $U(1)_X$-group. We explore the case in which the DM is a Majorana fermion. Furthermore, we provide parameter space regions allowed by current experimental constraints coming from the dark matter relic abundance, (in)direct detection, and charged lepton flavor violation.

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arXiv2019

Viable low-scale model with Universal and Inverse Seesaw Mechanisms

We formulate a viable low-scale seesaw model, where the masses for the standard model (SM) charged fermions lighter than the top quark emerge from a universal seesaw mechanism mediated by charged vectorlike fermions. The small light active neutrino masses are produced from an inverse seesaw mechanism mediated by right-handed Majorana neutrinos. Our model is based on the $A_{4} $ family symmetry, supplemented by cyclic symmetries, whose spontaneous breaking produces the observed pattern of SM fermion masses and mixings. The model can accommodate the muon and electron anomalous magnetic dipole moments and predicts strongly suppressed $μ\rightarrow eγ$ and $τ\rightarrow μγ$ decay rates, but allows a $τ\rightarrow eγ$ decay within the reach of the forthcoming experiments.

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