arXiv subjects

N. T. Duy

Publications and source records attributed to N. T. Duy.

16 recordsLinked to original sources

arXiv2026

Constraints from the SM-like Higgs boson in a flavor-dependent $U(1)$ extension of the Standard Model

This work presents a phenomenological study of the Standard Model-like Higgs boson $H$ in a flavor-dependent $U(1)_X$ extension of the Standard Model, where the $X$ charge is assigned according to fermion flavors. In particular, we analyze the interactions of $H$ with Standard Model particles as well as with new charged scalar bosons. In addition, the parameter $\ka_{\ga}$, which characterizes the $H\to \ga\ga$ decay at the one-loop level, is investigated. The results show that the model predicts $\ka_{\ga}$ values consistent with the ATLAS and CMS constraints at the $1σ$ level, while satisfying several bounds derived from flavor, collider and dark matter studies.

hep-ph↗

arXiv2026

A Minimal Dark $U(1)_D$ Framework for Inverse Seesaw Neutrino Masses and Dark Matter

We propose a minimal framework based on a dark $U(1)_D$ gauge symmetry that simultaneously accounts for neutrino masses and dark matter within an inverse seesaw realization. In this setup, the smallness of light neutrino masses is controlled, suppressed by a lepton-number violating parameter $μ$, which arises dynamically by dark field corrections rather than being introduced by hand. The limit $μ\to 0$ restores lepton number symmetry, ensuring its, thus neutrino mass, smallness in the sense of 't Hooft naturalness. We analyze the neutrino mass matrix and active-sterile mixing, highlighting their impact on non-unitarity and charged lepton flavor violation. The model is consistent with current experimental constraints while allowing potentially observable signals, such as $μ\to e γ$. The dark $U(1)_D$ symmetry stabilizes the dark matter candidate and links the neutrino and dark sectors. Viable parameter regions satisfying dark matter relic density, direct detection, and collider bounds are identified. This framework provides a minimal and predictive realization of neutrino mass generation and dark matter stability with a naturally small $μ$ parameter.

hep-ph↗

arXiv2026

Two-component dark matter from a flavor-dependent $U(1)$ gauge extension

We revisit the dark matter phenomenology of a flavor-dependent $U(1)_X$ gauge extension of the Standard Model, where anomaly cancellation predicts the existence of exactly three fermion generations and requires the presence of three right-handed neutrinos. In Ref.~\cite{VanLoi:2023utt}, a strong hierarchy between the vacuum expectation values of two singlet scalars, $\La_2 \gg \La_1$, renders all $\mathbb{Z}_2$-odd scalar states heavy, resulting in a two-component dark matter scenario composed exclusively of fermions. In the present work, we relax this simplifying assumption and consider a more general mass spectrum. In particular, scalar mixing can naturally lead to a situation in which the lightest $\mathbb{Z}_2$-odd particle is a scalar rather than a fermion. As a consequence, the model admits a qualitatively new realization of two-component dark matter consisting of one fermionic and one scalar component, in addition to the purely fermionic scenario studied previously. We perform a dedicated phenomenological analysis of these two-component dark matter realizations, focusing on the coupled thermal freeze-out dynamics and the resulting relic abundance. Constraints from the observed relic density and current direct-detection limits are taken into account, and viable regions of parameter space are identified.

hep-ph↗

arXiv2026

Extended IDM theory with low scale seesaw mechanisms

We have developed an extension of the inert doublet model in which the CP-phases in the weak sector are generated from one-loop level corrections mediated by dark fields, while the strong-CP phase arises at three-loop. In this framework, the tiny masses of the active neutrinos are produced through a radiative inverse seesaw mechanism at a two-loop level, the masses of the first and second families of SM-charged fermions arise from a one-loop level radiative seesaw mechanism, and the third generation of SM charged fermion masses are generated at tree level. We have demonstrated that the proposed model successfully accounts for SM fermion masses and mixings. The radiative nature of the seesaw mechanisms is attributed to preserved discrete symmetries, which are required for ensuring the stability of fermionic and scalar dark matter candidates. The preserved discrete symmetries also allow for multi-component dark matter, whose annihilation processes permits to successfully reproduce the measured amount of dark matter relic abundance for an appropriate region of parameter space, which has shown to be compatible with current dark matter direct detection limits. Besides that, we explore the model's ability to explain the $95$ GeV diphoton excess observed by the CMS collaboration, showing that it readily accommodates this anomaly. We have shown that charged lepton flavor violating decays acquire rates within the current experimental sensitivity.

hep-ph↗

arXiv2026

Physical implications of a double right-handed gauge symmetry

Guided by the flipping principle, we propose a novel extension of the Standard Model based on a double right-handed $U(1)$ gauge symmetry. In this framework, all left-handed fermions are neutral, while right-handed fermions of the third generation carry charges distinct from those of the first two generations. This structure naturally explains the observed Standard Model fermion mass hierarchy: the heavy masses of the third generation are generated at tree level, while the lighter masses of the first and second generations arise radiatively at the one-loop level. For the active neutrino sector, the tiny masses are generated through a combination of tree-level and two-loop seesaw mechanisms. Crucially, this approach successfully reproduces the observed neutrino mass hierarchy, with the atmospheric mass-squared difference generated at tree level and the solar neutrino mass squared difference emerging at the two-loop level. These hierarchical patterns stem from the interplay between gauge invariance and a residual parity symmetry that survives the spontaneous breaking of the extended gauge group. The same residual symmetry stabilizes a viable scalar singlet dark matter candidate, which we show can reproduce the observed relic abundance while remaining consistent with current direct detection bounds. After addressing constraints from electroweak precision tests and flavor-changing neutral currents, we explore the discovery prospects for the new neutral bosons at existing and future colliders, including the LEP, LHC, and a future ILC.

hep-ph↗

arXiv2025

Tri-hypercharge versus tri-darkcharge

We propose a minimal, ultraviolet-complete, and renormalizable extension of the Standard Model, in which the three generations of ordinary fermions are distinguished by family-dependent hypercharges, while three right-handed neutrinos are separated by a dark gauge symmetry that is trivial for all Standard Model fields. This setup yields a fully flipped inert doublet model. The model naturally realizes a hybrid scotoseesaw mechanism that accounts for the smallness of neutrino masses and the largeness of lepton mixing. Simultaneously, it explains the stability and relic abundance of dark matter through a residual dark parity and addresses the hierarchies of charged fermion masses and the suppression of quark mixing via higher-dimensional operators involving high-scale scalar singlets and vector-like fermions. We explore the phenomenological implications of the model and derive constraints from electroweak precision tests, collider searches, flavor-changing processes, and observations of dark matter.

hep-ph↗

arXiv2025

Flavor phenomenology of an extended 2HDM with inverse seesaw mechanism

We perform a detailed and comprehensive study of several flavor physics observables in both lepton and quark sectors within the framework of an extended 2HDM theory where the inverse seesaw mechanism is implemented to generate the SM fermion mass hierarchy. In that theory, the SM gauge symmetry is supplemented by the local $U(1)_X$ and discrete $Z_4\times Z_2$ groups. In particular, we find that the leptonic flavor observables specifically, the branching ratios of LFV decays $μ\to eγ, τ\to e(μ)γ$ and the anomalous magnetic moments $Δa_{e(μ)}$ strongly depend on the couplings of the neutral CP even(odd) Higgses with exotic charged lepton $E_1$, whereas other observables involving BR($l\to 3l'$), Mu-$\overline{\text{Mu}}$ transition and coherent conversion $μ\to e $ in a muonic atom are predicted to be less than several orders of magnitude compared to the corresponding experimental limits. Regarding the quark sector, the most stringent limits arising from the FCNC process involving the down-type quark $d_a\to d_b$ ($a=1,2,3$) transitions such as BR($\bar{B}\to X_s γ$), BR$(B_s\to μ^+μ^-)$, and meson mixing $ Δm_{K,B_s, B_d}$. Considering the obtained constraints from these observables, the new physics contributions to other observables namely BR$(B_s\to τ^+μ^-)$, BR$(B^+\to K^+τ^+τ^-)$, BR$(B^+\to K^+τ^+μ^-)$, and FCCC $b\to c$ transition LFUV ratios $R_{D^{(*)}}$ are shown to be remarkably small. Regarding the observables in the up-type quark transitions, the FCNC top quark processes $t\to u(c)γ$ and $t\to u(c)h$ have branching ratios consistent with the experimental limits. Additionally, observables related to SM-like Higgs boson decays BR$(h\to \bar{l}'l)$ and modified couplings $a_{h\bar{f}f}$ are also discussed.

hep-ph↗

arXiv2025

Scoto-seesaw model implied by flavor-dependent Abelian gauge charge

Assuming fundamental fermions possess a new Abelian gauge charge that depends on flavors of both quark and lepton, we obtain a simple extension of the Standard Model, which reveals some new physics insights. The new gauge charge anomaly cancellation not only explains the existence of just three fermion generations as observed but also requires the presence of a unique right-handed neutrino $ν_R$ with a non-zero new gauge charge. Further, the new gauge charge breaking supplies a residual matter parity, under which the fundamental fermions and $ν_R$ are even, whereas a right-handed neutrino $N_R$ without the new charge is odd. Consequently, light neutrino masses in our model are generated from the tree-level type-I seesaw mechanism induced by $ν_R$ and from the one-loop scotogenic contribution accommodated by potential dark matter candidates, $N_R$ and dark scalars, odd under the matter parity. We examine new physics phenomena related to the additional gauge boson, which could be observed at colliders. We analyze the constraints imposed on our model by current experimental limits on neutrino masses, neutral meson oscillations, $B$-meson decays, and charged lepton flavor violating processes. We also investigate the potential dark matter candidates by considering relic density and direct detection.

hep-ph↗

arXiv2024

Flavor-changing phenomenology in a $U(1)$ model

We investigate a family-nonuniversal Abelian extension of hypercharge, which significantly alters the phenomenological features of the standard model. Anomaly cancellation requires that the third quark family transforms differently from the first two quark families. Additionally, it acquires that three right-handed neutrinos are presented. This model generates naturally small neutrino masses and a $W$-boson mass deviation appropriate to recent measurements. Additionally, the model introduces flavor-changing neutral currents (FCNCs) of quarks coupled to the new gauge boson $Z'$ and new Higgs fields. These FCNCs significantly modify the neutral-meson mixing amplitudes and rare meson decays, which are studied in detail. We also address flavor changing processes in the charged lepton sector.

hep-ph↗

arXiv2024

Questions of flavor physics and neutrino mass from a flipped hypercharge

The flavor structure of quarks and leptons is not yet fully understood, but it hints a more fundamental theory of non-universal generations. We therefore propose a simple extension of the Standard Model by flipping (i.e., enlarging) the hypercharge $U(1)_Y$ to $U(1)_X\otimes U(1)_N$ for which both $X$ and $N$ depend on generations of both quark and lepton. By anomaly cancellation, this extension not only explains the existence of just three fermion generations as observed but also requires the presence of a right-handed neutrino per generation, which motivates seesaw neutrino mass generation. Furthermore, in its minimal version with a scalar doublet and two scalar singlets, the model naturally generates the measured fermion-mixing matrices while it successfully accommodates several flavor anomalies observed in the neutral meson mixings, $B$-meson decays, lepton-flavor-violating processes of charged leptons, as well as satisfying constraints from particle colliders.

hep-ph↗

arXiv2023

Lepton universality violation in the MF331 model

We perform a detailed study of the $\text{b} \to \text{c} τν$ and $\text{b} \to \text{s} l^+ l^-$ processes in a minimal flipped 331 model based on the $SU(3)_C\times SU(3)_L\times U(1)_N$ gauge symmetry. The non universal $SU(3)_L \times U(1)_N$ symmetry in the lepton sector gives rise to non universal neutral and charged currents involving heavy non SM gauge bosons and SM leptons that yield radiative contributions to the $b \to s$, $b\to c$, $s\to u$ and $d\to u$ transitions arising from one loop level penguin and box diagrams. We found that the observables related to these transitions agree with their experimental values in a region of parameter space that includes TeV scale exotic up type quarks, within the LHC's reach.

hep-ph↗

arXiv2022

New physics in $\text{b} \rightarrow \text{s}$ transitions in the MF331 model

There are two sources that help to explain the $\text{R}_\text{K}$, $\text{R}_{\text{K}^*}$ anomalies in the MF331 model. The first is non-LFUV couplings of the new neutral gauge boson $\text{Z}^{\prime}$ with leptons, $\text{g}^{\text{Z}^\prime}(e)\neq \text{g}^{\text{Z}^\prime}(μ,τ)$, which causes the $\text{R}_\text{K}$, $\text{R}_{\text{K}^*}$ anomalies via $\text{Z}^\prime$-penguin diagrams involving newly charged gauge bosons $\text{X}^{\pm}_μ$, and exotic U-quarks. The box diagram's contribution is the second source, which induced only the first lepton generation. We show that the penguin diagrams can not explain $\text{R}_\text{K}$, $\text{R}_{\text{K}^*}$ anomalies, and that the box diagram is required. The experimental constraints for $\text{R}_\text{K}$ and $\text{R}_{\text{K}^*}$ result in new particle mass degeneracy. The contributions of NP to the branching ratios $\text{Br}(\text{B}\to μ^+ μ^-), \text{Br}(\text{b}\to s γ)$ predict results that agree with the experimental limits in the allowed region of the NP scale.

hep-ph↗

arXiv2021

Physical constraints derived from FCNC in the 3-3-1-1 model

We investigate several phenomena related to FCNCs in the $\text{3-3-1-1}$ model. The sources of FCNCs at the tree-level from both the gauge and Higgs sectors are clarified. Experiments on the oscillation of mesons most stringently constrain the tree-level FCNCs. The lower bound on the new physics scale is imposed more tightly than in the previous, $\text{M}_{\text{new}}>12 $ \text{TeV}. Under this bound, the tree-level FCNCs make a negligible contribution to the $\text{Br}(B_s \rightarrow μ^+ μ^-)$, $\text{Br}(B \rightarrow K^{*} μ^+ μ^-)$ and $\text{Br}(B^{+}\rightarrow K^{+}μ^{+}μ^{-})$. The branching ratio of radiative decay $b \rightarrow s γ$ is enhanced by the ratio $\frac{v}{u}$ via diagrams with the charged Higgs mediation. In contrast, the charged currents of new gauge bosons significantly contribute to the decay process $μ\rightarrow e γ$.

hep-ph↗

arXiv2020

Investigation of Higgs boson anomalous FCNC interactions in the simple 3-3-1 model

We study phenomenological constraints on a simple $3-3-1$ model with flavor violating Yukawa couplings. Both triplets Higgs couple to leptons and quarks, which generates flavor violating signals in both lepton and quark sectors. We have shown that this model can allow for large Higgs lepton flavor-violating rate decay $h \rightarrow μτ$ and also can be reached to perfect agreements with other experimental constraints such as $τ\rightarrow μγ$ and $(g-2)_μ$. The contributions of flavor-changing neutral current (FCNC) couplings, Higgs-quark-quark couplings, to the mesons mixing are investigated. Br$(h \rightarrow q q^\prime )$ can be enhanced with keeping from the measurements of meson mixing. The branching ratio for $t \rightarrow q h$ can reach up to $10^{-3}$, but it could be as low as $10^{-8}$.

hep-ph↗

arXiv2019

Flavor changing in the flipped trinification

The flipped trinification, a framework for unifying the 3-3-1 and left-right symmetries, has recently been proposed in order to solve profound questions, the weak parity violation and the number of families, besides the implication for neutrino mass generation and dark matter stability. In this work, we argue that this gauge-completion naturally provides flavor-changing neutral currents in both quark and lepton sectors. The quark flavor changing happens at the tree-level due to the nonuniversal couplings of $Z'_{L,R}$, while the lepton flavor changing $l\rightarrow l'γ$ starts from the one loop level contributed significantly by the new charged currents of $Y_{L,R}$, which couple ordinary to exotic leptons. These effects disappear in the minimal left-right model, but are present in the framework characterizing a flipped trinification symmetry.

hep-ph↗

arXiv2018

Investigation of Dark Matter in the 3-2-3-1 Model

We prove that the $SU(3)_C\otimes SU(2)_L \otimes SU(3)_R\otimes U(1)_X$ (3-2-3-1) gauge model always contains a matter parity $W_P=(-1)^{3(B-L)+2s}$ as conserved residual gauge symmetry, where $B-L=2(βT_{8R}+X)$ is a $SU(3)_R\otimes U(1)_X$ charge. Due to the non-Abelian nature of $B-L$, the $W$-odd and $W$-even fields are actually unified in gauge multiplets. We investigate two viable versions for dark matter according to $β=\pm1/\sqrt{3}$, where the dark matter candidates can be fermion, scalar, or vector fields. We figure out the parameter spaces in the allowed regions of the relic density and direct detection cross-sections. Additionally, we examine the neutrino masses induced by the seesaw mechanism along with associated lepton flavor violation processes. The new gauge boson searches at the LEPII and LHC are discussed.

hep-ph↗