arXiv subjects

José W. F. Valle

Publications and source records attributed to José W. F. Valle.

At least 19 recordsLinked to original sources

arXiv2026

Zooming in on `bi-large' neutrino mixing with the first JUNO results

The leptonic mixing matrix is examined within bi-large mixing patterns and confronted with the latest results announced by the Jiangmen Underground Neutrino Observatory (JUNO). We analyze the viability of bi large mixing schemes and assess JUNO's ability to test neutrino mixing and discriminate among different bi-large mixing patterns, some of which are strongly disfavored when compared with neutrino oscillation global-fit results. Specific octant and CP predictions emerge. Finally, we comment on the implications of JUNO's findings for neutrinoless double beta decay.

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arXiv2026

Probing lepton number violation at FCC-ee

We propose high-multiplicity final-state signatures, such as $e^+e^-\to N\overline{N}\to \ell^+\ell^+ 4j$ with $\ell$ denoting $e,~μ$, $τ$, as probes of lepton number violation (LNV) at FCC-ee, featuring negligible Standard Model background. In contrast to conventional searches such as $pp\to \ell^+ N \to \ell^+ \ell^+ jj$ or the process $e^+e^-\toνN$, which are suppressed by the small neutrino masses in conventional seesaw scenarios, the minimal linear seesaw picture avoids this suppression. This enables a direct LNV probe from final-state topology, with over $\mathcal{O}(10^3)$ events expected at FCC-ee. Besides probing the Majorana nature of neutrinos, this offers a novel avenue to test the neutrino mass ordering established by oscillation experiments in a high-energy collider setting.

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arXiv2026

Dark matter as the source of neutrino mass: theory overview and experimental prospects

We review theoretical frameworks in which small neutrino masses arise radiatively through interactions with a dark sector that also accounts for cosmological dark matter (DM). A prototype is provided by scotogenic schemes, that extend the inert Higgs doublet model to include dark fermions. We outline their key features and limitations, discussing the advantages of the revamped scotogenic extension. The phenomenological signatures of fermionic and bosonic scotogenic dark matter are discussed, along with scoto-seesaw models that merge scotogenic and seesaw mechanisms. We also consider scenarios where the dark sector seeds a low-scale seesaw. These frameworks can accommodate dark matter as Weakly or Feebly Interacting Massive Particles (WIMPs or FIMPs). While hidden dark sector models are inherently difficult to exclude, visible dark sector schemes should be confirmed--or ruled out--by forthcoming dark matter, collider, and lepton flavor violation studies.

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arXiv2025

Flavor-changing axions and Dirac neutrino masses

Implementing the axion concept in the context of 3-3-1 extensions of the Standard Model (SM) leads to richer properties than in the simpler axion setups, and related to the Dirac neutrino seesaw mechanism. In this way the smallness of neutrino masses, the strong CP problem, the nature of dark matter and the number of families all have a common origin. Besides having an enhanced coupling to photons, our revamped axion can also be distinguished from DFSZ and KSVZ axions through its couplings to fermions. The latter lead to interesting phenomenological consequences, including flavor-changing axion-emitting two-body K, B and D meson decays.

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arXiv2025

QCD axion, colour-mediated neutrino masses, and $B^+\to K^+ + E_{\text{miss}}$ anomaly

Motivated by the recent Belle II result indicating a $2.7\,σ$ excess of $B^+\to K^+ + E_{\text{miss}}$ events compared to the Standard Model (SM) prediction for $B^+ \to K^+ ν\barν$, we explore an explanation to this anomaly based on a KSVZ-type QCD axion model featuring a Peccei-Quinn (PQ) symmetry breaking at high-scale, that can provide a solution to the strong CP problem with dark matter relic abundance. The model contains a PQ-charged scalar} leptoquark which can interact with the SM quarks only via mass-mixing of the latter with vector-like quarks. The mixing between SM and vector-like quarks is determined by the PQ mass scales and can explain the excess $B^+\to K^+ + E_{\text{miss}}$ events while respecting other flavour constraints. The same PQ-charged scalar leptoquarks and vector-like quarks also mediate the two-loop radiative neutrino masses.

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arXiv2024

Large lepton number violation at colliders: predictions from the minimal linear seesaw mechanism

Small neutrino masses can be sourced by a tiny vacuum expectation value of a leptophilic Higgs doublet, and mediated by Quasi-Dirac heavy neutrinos. In such simplest linear seesaw picture the neutrino mass mediators can be accessible to colliders. We describe novel charged Higgs and heavy neutrino production mechanisms that can be sizeable at $e^+ e^-$, $e^- γ$, $pp$, or muon colliders and discuss some of the associated signatures. The oscillation length of the heavy neutrino mediators is directly related to the light neutrino mass ordering. Moreover, lepton number violation can be large despite the smallness of neutrino masses, and may shed light on the Majorana nature of neutrinos and the significance of basic symmetries in weak interaction.

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arXiv2024

Dynamical scoto-seesaw mechanism with gauged $B-L$

We propose a dynamical scoto-seesaw mechanism using a gauged $B-L$ symmetry. Dark matter is reconciled with neutrino mass generation, in such a way that the atmospheric scale arises \textit{a la seesaw}, while the solar scale is \textit{scotogenic}, arising radiatively from the exchange of ``dark'' states. This way we ``explain'' the solar-to-atmospheric scale ratio. The TeV-scale seesaw mediator and the two dark fermions carry different $B-L$ charges. Dark matter stability follows from the residual matter parity that survives $B-L$ breaking. Besides having collider tests, the model implies sizeable charged lepton flavour violating (cLFV) phenomena, including Goldstone boson emission processes.

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arXiv2024

Quark-lepton mass relations from modular flavor symmetry

The so-called Golden Mass Relation provides a testable correlation between charged-lepton and down-type quark masses, that arises in certain flavor models that do not rely on Grand Unification. Such models typically involve broken family symmetries. In this work, we demonstrate that realistic fermion mass relations can emerge naturally in modular invariant models, without relying on ad hoc flavon alignments. We provide a model-independent derivation of a class of mass relations that are experimentally testable. These relations are determined by both the Clebsch-Gordan coefficients of the specific finite modular group and the expansion coefficients of its modular forms, thus offering potential probes of modular invariant models. As a detailed example, we present a set of viable mass relations based on the $Γ_4\cong S_4$ symmetry, which have calculable deviations from the usual Golden Mass Relation.

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arXiv2024

Phenomenological profile of scotogenic fermionic dark matter

We consider the possibility that neutrino masses arise from the exchange of dark matter states. We examine in detail the phenomenology of fermionic dark matter in the singlet-triplet scotogenic reference model. We explore the case of singlet-like fermionic dark matter, taking into account all co-annihilation effects relevant for determining its relic abundance, such as fermion-fermion and scalar-fermion co-annihilation. Although this in principle allows for dark matter below 60 GeV, the latter is in conflict with charged lepton flavour violation (cLFV) and/or collider physics constraints. We examine the prospects for direct dark matter detection in upcoming experiments up to 10 TeV. Fermion-scalar coannihilation is needed to obtain viable fermionic dark matter in the 60-100 GeV mass range. Fermion-fermion and fermion-scalar coannihilation play complementary roles in different parameter regions above 100 GeV.

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arXiv2023

Synergy between cosmological and laboratory searches in neutrino physics

The intersection of the cosmic and neutrino frontiers is a rich field where much discovery space still remains. Neutrinos play a pivotal role in the hot big bang cosmology, influencing the dynamics of the universe over numerous decades in cosmological history. Recent studies have made tremendous progress in understanding some properties of cosmological neutrinos, primarily their energy density. Upcoming cosmological probes will measure the energy density of relativistic particles with higher precision, but could also start probing other properties of the neutrino spectra. When convolved with results from terrestrial experiments, cosmology can become even more acute at probing new physics related to neutrinos or even Beyond the Standard Model (BSM). Any discordance between laboratory and cosmological data sets may reveal new BSM physics and/or suggest alternative models of cosmology. We give examples of the intersection between terrestrial and cosmological probes in the neutrino sector, and briefly discuss the possibilities of what different laboratory experiments may see in conjunction with cosmological observatories.

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arXiv2023

Linear seesaw mechanism from dark sector

We propose a minimal model where a dark sector seeds neutrino mass generation radiatively within the linear seesaw mechanism. Neutrino masses are calculable, since tree-level contributions are forbidden by symmetry. They arise from spontaneous lepton number violation by a small Higgs triplet vacuum expectation value. Lepton flavour violating processes e.g. $μ\to eγ$ can be sizeable, despite the tiny neutrino masses. We comment also on dark-matter and collider implications.

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arXiv2023

Phenomenology of the simplest linear seesaw mechanism

The linear seesaw mechanism provides a simple way to generate neutrino masses. In addition to Standard Model particles, it includes quasi-Dirac leptons as neutrino mass mediators, and a leptophilic scalar doublet seeding small neutrino masses. Here we review its associated physics, including restrictions from theory and phenomenology. The model yields potentially detectable $μ\to eγ$ rates as well as distinctive signatures in the production and decay of heavy neutrinos ($N_i$) and the charged Higgs boson ($H^\pm$) arising from the second scalar doublet. We have found that production processes such as $e^+e^-\to NN$, $e^-γ\to NH^-$ and $e^+ e^-\to H^+ H^-$ followed by the decay chain $H^\pm\to\ell_i^\pm N$, $N\to \ell_j^{\pm}W^\mp$ leads to striking lepton number violation signatures at high energies which may probe the Majorana nature of neutrinos.

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arXiv2023

Scotogenic majorana neutrino masses in a predictive orbifold theory of flavour

The use of extra space-time dimensions provides a promising approach to the flavour problem. The chosen compactification of a 6-dimensional orbifold implies a remnant family symmetry $A_4$. This makes interesting predictions for quark and lepton masses, for neutrino oscillations and neutrinoless double beta decay, providing also a very good global description of all flavour observables. Due to an auxiliary $\mathbb{Z}_4$ symmetry, we implement a scotogenic Majorana neutrino mass generation mechanism with a viable WIMP dark matter candidate.

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arXiv2022

Revamping Kaluza-Klein dark matter in an orbifold theory of flavor

We suggest a common origin for dark matter, neutrino mass and family symmetry within the orbifold theory proposed in [arXiv:1910.05605v2,arXiv:2004.06735v2]. Flavor physics is described by an $A_4$ family symmetry that results naturally from compactification. WIMP Dark matter emerges from the first Kaluza-Klein excitation of the same scalar that drives family symmetry breaking and neutrino masses through the inverse seesaw mechanism. In addition to the "golden" quark-lepton mass relation and neutrino predictions for $0νββ$ decay, the model provides a good global description of all flavor observables.

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arXiv2022

Physics implications of recent Dresden-II reactor data

Prompted by the recent Dresden-II reactor data we examine its implications for the determination of the weak mixing angle, paying attention to the effect of the quenching function. We also determine the resulting constraints on the unitarity of the neutrino mixing matrix, as well as on the most general type of nonstandard neutral-current neutrino interactions.

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arXiv2022

W-mass Anomaly in the Simplest Linear Seesaw Mechanism

The simplest linear seesaw mechanism can accommodate the new CDF-II $W$ mass measurement. In addition to Standard Model particles, the model includes quasi-Dirac leptons, and a second, leptophilic, scalar doublet seeding small neutrino masses. Our proposal is consistent with electroweak precision tests, neutrino physics, rare decays and collider restrictions, requiring a new charged scalar below a few TeV, split in mass from the new degenerate scalar and pseudoscalar neutral Higgs bosons.

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arXiv2022

Interpreting B-anomalies within an extended 331 gauge theory

In light of the recent $R_{K^{(*)}}$ data on neutral current flavour anomalies in $B \to K^{(*)} \ell^+ \ell^-$ decays, we re-examine their quantitative interpretation in terms of an extended 331 gauge theory framework. We achieve this by adding two extra lepton species with novel 331 charges, while ensuring that the model remains anomaly free. In contrast to the canonical 331 models, the gauge charges of the first and second lepton families differ from each other, allowing lepton flavour universality violation. We further expand the model by adding the neutral fermions required to provide an adequate description for small neutrino masses.

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arXiv2021

Scotogenic neutrino masses with gauged matter parity and gauge coupling unification

Building up on previous work we propose a Dark Matter (DM) model with gauged matter parity and dynamical gauge coupling unification, driven by the same physics responsible for scotogenic neutrino mass generation. Our construction is based on the extended gauge group \3311, whose spontaneous breaking leaves a residual conserved matter parity, $M_{P}$, stabilizing the DM particle candidates of the model. A key role is played by the Majorana ${\rm SU(3)_{L}}$-octet leptons, in allowing successful gauge coupling unification and one-loop scotogenic neutrino mass generation. Theoretical consistency allows for a \emph{plethora} of new particles at the $\lsim \mathcal{O}$(10) TeV scale, hence accessible to future collider and low-energy experiments.

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