arXiv subjects

Yithsbey Giraldo

Publications and source records attributed to Yithsbey Giraldo.

At least 19 recordsLinked to original sources

arXiv2026

Linking Axions, the Flavor Problem, and Neutrino Masses through a Flavored Peccei-Quinn Symmetry

Recent measurements by several experimental collaborations have reported deviations from Standard Model (SM) predictions in diphoton final states, potentially hinting at the existence of intermediate scalar resonances above the electroweak scale. Such anomalies can be naturally accommodated within SM extensions featuring an enlarged scalar sector. In particular, multi-Higgs doublet frameworks arise in Flavored Axion Models (FAMs), which have been proposed to explain the texture zeros of quark mass matrices. These models provide a unified description of quark masses and the Cabibbo-Kobayashi-Maskawa (CKM) mixing matrix while simultaneously addressing the strong CP problem. In this work we study a concrete FAM realization augmented with Majorana masses for right-handed neutrinos, implementing a type-I seesaw mechanism. In this model the flavor structure is effectively determined by the vacuum expectation values of the scalar doublets and Yukawa couplings of order one. Within this framework, neutrino and axion mass scales are intrinsically connected, as the heavy right-handed neutrinos obtain their masses from the scalar field responsible for the spontaneous breaking of the Peccei-Quinn symmetry. We further explore the phenomenological implications of the model, including constraints from flavor-changing neutral currents derived from semileptonic decays, as well as current experimental limits on the axion-photon coupling obtained from axion search experiments.

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arXiv2025

Non-Universal Flipped Trinification Models with Arbitrary $β$

We explore the recently proposed gauge symmetry $ SU(3)_C \otimes SU(3)_L \otimes SU(3)_R \otimes U(1)_X $, which naturally embeds both the Left-Right symmetric model and the 3-3-1 model as subgroups. Within this unified framework, we propose four families of leptons and quarks. A detailed analysis of their contributions to gauge anomaly cancellation is carried out for a general value of the parameter $β$. From this analysis, eight non-universal anomaly-free three-family models and four non-universal two-family anomaly free sets were identified. The three-family models offer realistic extensions of the Standard Model, retaining several appealing features of the 3-3-1 models, while the two-family sets provide flexibility for constructing models with even numbers of families. We also report LHC bounds on the $Z'$ mass for the particular case $β= -1/\sqrt{3}$, considering all possible combinations of lepton and quark families. These limits exhibit a strong dependence on the mixing parameter $θ$, which enters the couplings of Standard Model fermions to the $Z'$ boson.

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arXiv2025

The Standard Model of Particle Physics as an effective theory from two non-universal $U(1)$'s

We study the possibility of obtaining the Standard Model (SM) of particle physics as an effective theory of a more fundamental one, whose electroweak sector includes two non-universal local $U(1)$ gauge groups, with the chiral anomaly cancellation taking place through an interplay among families. As a result of the spontaneous symmetry breaking, a massive gauge boson $Z'$ arises, which couples differently to the third family of fermions (by assumption, we restrict ourselves to the scenario in which the $Z'$ couples in the same way to the first two families). Two Higgs doublets and one scalar singlet are necessary to generate the SM fermion masses and break the gauge symmetries. We show that in our model, the flavor-changing neutral currents (FCNC) of the Higgs sector are identically zero if each right-handed SM fermion is only coupled with a single Higgs doublet. This result represents a FCNC cancellation mechanism different from the usual procedure in Two-Higgs Doublet Models~(2HDM). The non-universal nature of our solutions requires the presence of three right-handed neutrino fields, one for each family. Our model generates all elements of the Dirac mass matrix for quarks and leptons, which is quite non-trivial for non-universal models. Thus, we can fit all the masses and mixing angles with two scalar doublets. Finally, we show the distribution of solutions for the scalar boson masses in our model by scanning well-motivated intervals for the model parameters. We consider two possibilities for the scalar potential and compare these results with the Higgs-like resonant signals recently reported by the ATLAS and CMS experiments at the LHC. Finally, we also report collider, electroweak, and flavor constraints on the model parameters.

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arXiv2024

Alternative 3-3-1 models with exotic electric charges

We report the most general classification of 3-3-1 models with $β=\sqrt{3}$. We found several solutions where anomaly cancellation occurs among fermions of different families. These solutions are particularly interesting as they generate non-universal heavy neutral vector bosons. Non-universality in the SM fermion charges under an additional gauge group generates Charged Lepton Flavor Violation (CLFV) and Flavor Changing Neutral Currents~(FCNC); we discuss under what conditions the new models can evade constraints coming from these processes. In Addition, we also report LHC constraints.

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arXiv2023

A minimal axion model for mass matrices with five texture-zeros

A model with fermion and scalar fields charged under a Peccei-Queen~(PQ) symmetry is proposed. The PQ charges are chosen in such a way that they can reproduce mass matrices with five texture zeros, {which can generate} the fermion masses, the CKM matrix, and the PMNS matrix of the Standard Model~(SM). To obtain this result, at least 4~Higgs doublets are needed. As we will see in the manuscript this is a highly non-trivial result since the texture zeros of the mass matrices impose a large number of restrictions. This model shows a route to understand the different scales of the SM by extending it with a multi-Higgs sector and an additional PQ symmetry. Since the PQ charges are not universal, the model presents flavor-changing neutral currents~(FCNC) at the tree level, a feature that constitutes the main source of restrictions on the parameter space. We report the allowed regions by lepton decays and compare them with those coming from the semileptonic decays $K^{\pm}\longrightarrow π\barνν$. We also show the excluded regions and the projected bounds of future experiments for the axion-photon coupling as a function of the axion mass and compare it with the parameter space of our model.

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arXiv2022

Flavored axions and the flavor problem

A Peccei-Quinn~(PQ) symmetry is proposed in order to generate in the Standard Model~(SM) quark sector a realistic mass matrix ansatz with five texture-zeros. Limiting our analysis to Hermitian mass matrices, we show that this requires a minimum of 4 Higgs doublets. This model allows assigning values close to 1 for several Yukawa couplings, giving insight into the origin of the mass scales in the SM. Since the PQ charges are non-universal, the model features Flavor-Changing Neutral Currents~(FCNC) at the tree level. From the analytical expressions for the FCNC we report the allowed region in the parameter space obtained from the measurements of branching ratios of semileptonic meson decays.

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arXiv2021

Systematic study of the $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$ local gauge symmetry

We review in a systematic way how anomaly free $SU(3)_c\otimes SU(3)_L\otimes U(1)_x$ models without exotic electric charges can be constructed, using as basis closed sets of fermions which includes each one the particles and antiparticles of all the electrically charged fields. Our analysis reproduce not only the known models in the literature, but also shows the existence of several more independent models for one and three families not considered so far. A phenomenological analysis of the new models is done, where the lowest limits at a 95\% CL on the gauge boson masses are presented.

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arXiv2021

CKM mixings from mass matrices with five texture zeros

In this work we carry out an exhaustive study to find quark mass matrices in the Standard Model~(SM), with the maximum number of texture zeros consistent with the experimental data. We found four viable configurations of five texture zeros that adjust the quark masses, the mixing angles and the CP violation phase, with deviations below $1σ$ level respect to the current SM best fit values. One of the most important aspects of this work is an economic procedure to find the texture zeros: we resort to the weak basis transformation method, which, as we will show, exhaustively search every possible configuration. We report various leading order relations between the mixing angles and the quark masses for each case.

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arXiv2020

Five Texture Zeros for Dirac Neutrino Mass Matrices

In this work we propose new five textures zeros for the mass matrices in the lepton sector in order to predict values for the neutrino masses. In our approach we go beyond the Standard Model by assuming Dirac masses for the neutrinos, feature which allows us to make a theoretical prediction for the lightest neutrino mass in the normal ordering. The textures analyzed have enough free parameters to adjust the $V_{\text{\tiny PMNS}}$ mixing matrix including the CP-violating phase, the neutrino mass squared differences $δm_{21}^2,\,δm_{31}^2$, and the three charged lepton masses. In order to have reliable results two different approaches are used: the first one is based on a least-squares analysis to fit the lepton masses and the mixing parameters to their corresponding experimental values, for this case the best fit for the lightest neutrino mass is $(3.9\pm^{0.6}_{0.8})\times 10^{-3}$ eV.; the second approach is just algebraic, based on the weak basis transformation method, in this case the lightest neutrino mass consistent with the experimental values and the restrictions coming from the five texture zeros of the mass matrices is equal to $(3.5\pm0.9)\times 10^{-3}$ eV.

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arXiv2018

Five Non-Fritzsch Texture Zeros for Quarks Mass Matrices in the Standard Model

In the Standard Model, we obtain a non-Fritzsch like configuration with five texture zeros for the quark mass matrices. This matrix generates the quark masses, the inner angles of the CKM unitary triangle, and the CP-violating phase in the quark sector. This work can be applied to the PMNS matrix in the lepton sector, by assuming Dirac masses for the neutrinos, where non-trivial predictions for the neutrino masses and mixing angles are expected.

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arXiv2018

Revised Criteria for Stability in the General Two-Higgs Doublet Model

We will revise one of the methods given in the literature to determine the necessary and sufficient conditions that the parameters must satisfy to have a stable scalar potential in the general two-Higgs doublet model. We will give a procedure that facilitates finding the conditions for stability of a scalar potential. The stability guarantees that the scalar potential has a global minimum, that is, the potential is bounded from below, which is a necessary condition to implement the spontaneous gauge-symmetry breaking in the models.

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arXiv2015

Seeking Texture Zeros in the Quark Mass Matrix Sector of the Standard Model

Here we show that the Weak Basis Transformation is an appropriate mathematical tool that can be used to find texture zeros in the quark mass matrix sector of the Standard Model. So, starting with the most general quark mass matrices and taking physical data into consideration, is possible to obtain more than three texture zeros by any weak basis transformation. Where the most general quark mass matrices considered in the model, were obtained through a special weak basis wherein the mass matrix $M_u$~(or $M_d$) has been taken to be diagonal and only the matrix $M_d$~(or $M_u$) is considered to be most general.

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arXiv2015

Reply to "Comment on "Texture Zeros and WB Transformations in the Quark Sector of the Standard Model"

We respond to the comments of S. Sharma et al. [Phys. Rev. D 91, 038301 (2015)] on my recent paper, Y. Giraldo [Phys. Rev. D 86, 093021 (2012)]. In their comments, they begin discussing a particular class of five-zero texture non-Fritzsch-like quark mass matrix, which was proposed by me, and questioning its validity. Then, they put in doubt the phases included in the unitary matrices used for diagonalizing the quark mass matrices, from which they claim that the CP violating parameter $ε_k$ obtained does not agree with the experimental value. Because of these comments, finally, they recommend being careful while analyzing the implications of Weak Basis transformations on textures. Other minor points are also discussed by them. In the following, I will show that the mentioned five-zero texture non-Fritzsch-like quark mass matrices is completely valid and generates all the physical quantities involved, including the CP violating parameter $ε_k$, for which is required the inclusion of phases in the unitary matrices used for diagonalizing the quark mass matrices in order to put the CKM matrix in standard form. These phases can be rotated away so they do not have any physical meaning. Finally, the relevance of the weak basis transformation is appreciated: which is {\it complete} and facilitates calculations, especially of textures zeros.

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arXiv2012

Texture Zeros and WB Transformations in the Quark Sector of the Standard Model

Stimulated by the recent attention given to the texture zeros found in the quark mass matrices sector of the Standard Model, an analytical method for identifying (or to exclude) texture zeros models will be implemented here, starting from arbitrary quark mass matrices and making a suitable weak basis transformation, we are be able to find equivalent quark mass matrix. It is shown that the number of non-equivalent quark mass matrix representations is finite. We give exact numerical results for parallel and non-parallel four-texture zeros models. We find that some five-texture zeros Ans$\ddot{\textrm{a}}$tze are in agreement with all present experimental data. And we confirm definitely that six-texture zeros of Hermitian quark mass matrices are not viable models anymore.

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arXiv2011

$Z^{'0}Z^{'0}$, $K^{+}K^{-}$ and $K^{0}\bar{K}^{0}$ boson production with definite helicity amplitudes through $e^{+}e^{-}$ collisions in the 3-3-1 models without exotic electric charges

A detailed analysis of $Z^{'0}Z^{'0}$, $K^{+}K^{-}$ and $K^{0}\bar{K}^{0}$ pair production in $e^{+}e^{-}$ collisions is presented by using helicity amplitudes. The trilinear bosons couplings in the $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}$ models without exotic electric charges are also calculated. We carry out the mentioned analysis for two models, one of them is a one family model which is an $E_6$ subgroup \cite{b1} and the other one is a three family model with right handed neutrinos\cite{b2,b3}. These models do not contain exotic electric charges. For them, we give explicit formulae and the corresponding numerical estimates of the cross-sections and angular distributions occurred in the processes $e^{+}e^{-}\to Z^{'0}Z^{'0}$, $e^{+}e^{-} \to K^{+}K^{-}$ and $e^{+}e^{-}\to K^{0}\bar{K}^{0}$ present in our models. We suppose these processes are invariant under $C$, $P$ and $T$ transformation.

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arXiv2011

Scalar Potential Without Cubic Term in 3-3-1 Models Without Exotic Electric Charges

A detailed study of the criteria for stability of the scalar potential, and the proper electroweak symmetry breaking pattern in some 3-3-1 models without exotic electric charges is presented. In this paper we concentrate in a scalar sector with three Higgs scalar triplets, with a potential that does not include the cubic term, due to the presence of a discrete symmetry. For the analysis we use, and improve, a method previously developed to study the scalar potential in the two-Higgs-doublet extension of the standard model. Our main result is to show the consistency of those 3-3-1 models without exotic electric charges.

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arXiv2010

$SU(3)_c\otimes SU(3)_L\otimes U(1)_X$ models with four families

In the context of the local gauge group $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$, we look for possible four family models, where all the particles carry ordinary electric charges. Thirteen different anomaly-free fermion structures emerge, out of which only two are realistic. For the simplest physical structure, we calculate the charged and neutral weak currents and the tree-level Fermion masses. We also look for new sources of flavor changing neutral currents in the quark sector, in connection with the upcoming experimental results at the Large Hadron Collider.

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arXiv2009

FCNC in the 3-3-1 model with right-handed neutrinos

Flavor changing neutral currents coming from a new non-universal neutral Gauge-Boson and from the non-unitary quark mixing matrix for the $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$ model with right handed neutrinos are studied. By imposing as experimental constraints the measured values of the 3x3 quark mixing matrix, the neutral meson mixing, and the bounds measured values for direct flavor changing neutral current processes, the largest mixing of the known quarks with the exotic ones can be established, with new sources of flavor changing neutral currents being identified. Our main result is that for a $|V_{tb}|$ value smaller than one, large rates of rare top decays such as $t\to cγ$, $t\to cZ$, and $t\to cg$ (where g stands for the gluon field) are obtained; but if $|V_{tb}|\approx 1$ the model can survive present experimental limits only if the mass of the new neutral Gauge Boson becomes larger that 10 TeV.

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