arXiv subjects

Patricio Escalona

Publications and source records attributed to Patricio Escalona.

7 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 $μ\to e γ$, $μ\to 3e$, and $μ\to e$ 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 $χ$, 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

Three decades of FCNC studies in 3-3-1 model with right-handed neutrinos: from $Z^\prime$-dominance to the alignment limit

Flavor-changing neutral current (FCNC) processes play a prominent role in the search for physics beyond the Standard Model (SM) due to their sensitivity to new physics at the TeV scale. Meson-antimeson transitions and rare meson decays provide stringent constraints on new physics through precision measurements of observables such as mass differences, CP asymmetries, and branching ratios. Extensions of the SM based on the $\text{SU}(3)_C \times \text{SU}(3)_L \times \text{U}(1)_N$ gauge group offer a compelling framework for flavor physics, as FCNC processes emerge inexorably at tree level due to the non-universal transformations of the quark families. Among its various realizations, the version incorporating right-handed neutrinos (331RHN) is the most phenomenologically viable. This review synthesizes three decades of theoretical developments in FCNC phenomenology within the 331RHN model, from early $Z^\prime$-dominated studies to the recent recognition of the decisive role played by the SM-like Higgs boson and the identification of the alignment limit. We demonstrate that viable parameter space spans orders of magnitude, from $m_{Z^\prime} \sim$ a few hundred GeV to $\sim 100$ TeV, depending critically on quark mixing parametrizations and scalar alignment configurations, with significant implications for experimental searches at current and future colliders.

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arXiv2025

Type-II Seesaw Mechanism for Dirac Neutrinos and its Implications on $N_{\text{eff}}$ and Lepton Flavor Violation in a 3-3-1 model

In this study, we implement the type-II seesaw mechanism for Dirac neutrino masses within the framework of a 3-3-1 model. To this end, we introduce a scalar sextet and impose both lepton number conservation and invariance under a discrete $Z_2$ symmetry in the Lagrangian. This mechanism naturally generates small Dirac neutrino masses by allowing the soft breaking of the $Z_2$ symmetry through a unique term in the scalar potential, while preserving lepton number. Specifically, we explore the realization of this model at low-energy scales. Regarding flavor implications, we analyze its contributions to the rare decay processes $μ\to e γ$ and $μ\to \bar e ee$. In the cosmological context, we analyze the influence of right-handed neutrinos on the effective number of neutrino species, $N_\text{eff}$, through interactions mediated by the $Z^{\prime}$ boson. Our findings establish a lower bound of $m_{Z^{\prime}} > 4.4$ TeV, which slightly exceeds the current lower limit set by the Large Hadron Collider (LHC).

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arXiv2025

Meson Mixing Bounds on $Z^{\prime}$ Mass in the Alignment Limit: Establishing the Phenomenological Viability of the 331 Model

We perform a systematic study of flavor-changing neutral currents (FCNCs) in the 331 model with right-handed neutrinos (331RHNs), analyzing constraints on the $Z^\prime$ boson mass from $K$-, $D$-, $B_d$-, and $B_s$-meson oscillations. By explicitly incorporating scalar sector dynamics and quark rotation ambiguities ($V_L^{u,d}$), we demonstrate that $Z^\prime$ mass limits depend critically on the parametrization of Cabibbo-Kobayashi-Maskawa (CKM) matrix factors. Three scenarios are explored: (i) $V_L^u = V_\text{CKM}^\dagger$ (FCNCs restricted to $D$-mesons), (ii) $V_L^d = V_\text{CKM}$ (dominant $B_s$ constraints), and (iii) a hybrid mixing pattern. Strikingly, scenario (i) reduces the $Z^\prime$ mass bound to $M_{Z^\prime} \gtrsim 600\;\text{GeV}$-two orders of magnitude below literature values-by leveraging large experimental uncertainties in $D$-$\bar{D}$ oscillations. Conversely, scenario (ii) requires $M_{Z^\prime} \gtrsim 165\;\text{TeV}$ due to stringent $B_s$ data. We further establish the alignment limit $\cos(ϕ+φ) = 0$ for the SM-like Higgs, showing its viability depends on $V_L^{u,d}$ configurations, with $B_s$ systems enforcing $|\cos(ϕ+φ)| < 0.01$ in down-sector FCNC scenarios. Our analysis reveals that strategic choices of quark mixing matrices can suppress FCNC visibility, reconciling the 331 framework with flavor data without ultra-heavy $Z^\prime$ bosons. This work provides the first unified treatment of SM-like Higgs- and $Z^\prime$-mediated FCNCs in 331 models, identifying viable parameter spaces for collider phenomenology.

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arXiv2024

Vector Dark Matter from the 5-Dimensional Representation of $SU(2)_{L}$

The introduction of electroweak multiplets that transform under any representation of the standard $SU(2)_L$ gauge group suggests the existence of electrically neutral stable particles capable of serving as cold dark matter in the $Λ$CDM cosmological model. This paradigm, known as minimal dark matter, has primarily focused on spin-$0$ and spin-$1/2$ particles. We extend this study to the spin-1 case using the 5-dimensional real representation. We address unitarity concerns arising from the model's interactions with electroweak and Higgs fields of the Standard Model, investigating implications for dark matter relic density, direct and indirect detection, including non-perturbative Sommerfeld enhancement for the latter. Collider signatures of the proposed model are also examined. Our findings suggest that the model remains consistent with experimental constraints, particularly for dark matter masses on the order of dozens of TeV, and could potentially be tested using $γ$-ray observatories such as CTA.

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arXiv2021

Fermion Singlet Dark Matter in a Pseudoscalar Dark Matter Portal

We explore a simple extension to the Standard Model containing two gauge singlets: a Dirac fermion and a real pseudoscalar. In some regions of the parameter space both singlets are stable without the necessity of additional symmetries, then becoming a possible two-component dark matter model. We study the relic abundance production via freeze-out, with the latter determined by annihilations, conversions and semi-annihilations. Experimental constraints from invisible Higgs decay, dark matter relic abundance and direct/indirect detection are studied. We found three viable regions of the parameter space, and the model is sensitive to indirect searches.

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