arXiv subjects

J. L. Díaz-Cruz

Publications and source records attributed to J. L. Díaz-Cruz.

12 recordsLinked to original sources

arXiv2026

Fermion mass hierarchy and flavor signals from a $D_4$ dihedral symmetry within a 2HDM-Tx with four-zero textures

We propose an extended Texturized Two-Higgs Doublet Model (2HDM-Tx) where a discrete $D_4$ symmetry predicts a four-zero texture in the fermion mass matrices. In contrast to the standard ansatz where the underlying Yukawa matrices are assumed to be structurally identical, we introduce a novel configuration of non-equivalent matrices that complementarily generate a specific Hermitian four-zero mass structure. This framework naturally suppresses flavor-changing neutral currents and provides a structural rationale for the fermion mass hierarchy, while in addition including a dark matter candidate. As a concrete phenomenological application, we show that the model simultaneously accommodates the persistent neutral resonance excesses at $95\text{ GeV}$ and $152\text{ GeV}$, satisfies current \text{LHC} Higgs data, and is consistent with the stringent upper bounds from lepton flavor violation processes. These combined constraints severely restrict the parameter space of the scalar phenomenology. Finally, we study the prospects for the discovery of the lepton-flavor violating process $h \to τμ$ at the High-Luminosity LHC.

hep-ph↗

arXiv2025

Single Higgs boson production in association with a top quark through FCNSI

We study the production and possible detection of a single Higgs boson in association with a top quark in proton-proton collisions ($pp \to th + X$) at the High-Luminosity Large Hadron Collider. This process absent in the Standard Model is predicted by other models such as the Two-Higgs Doublet Model of type III, which is the theoretical framework adopted in this work. Promising results are found for specific scenarios of the model parameter space, which consist mainly of the parameters $\tanβ$, $\cos(α-β)$ and the parameter $χ_{tc}$, responsible for the Flavor-Changing Neutral Scalar Interactions (FCNSI). Using the machine learning \textit{Boosted Decision Trees} algorithm and considering a systematic uncertainty of $5\%$, we predict \textit{signal significances} at level of $5σ$ for $\tanβ=1$, $\cos(α-β)=0.1$, $χ_{tc}=5$, and integrated luminosities {$\mathcal{L}_{\rm int}\gtrsim2700~fb^{-1}$}. Likewise, we also predict a \textit{signal significance} $σ\approx 4.4$ for $\tanβ=1$, $\cos(α-β)=0.1$, $χ_{tc}=3$, and integrated luminosities $\mathcal{L}_{\rm int} = 3000~fb^{-1}$, which consider the upper limit given by HL-LHC projection on $\mathcal{BR}(t\to ch)$.

hep-ph↗

arXiv2025

Discrete Symmetries in the Chiral Fermion Formalism

In this paper, we present a revision of the discrete symmetries (C, P, T, CP, and CPT) within an approach that treats 2-component Weyl spinors as the fundamental building blocks. In particular, we show that we can define transformations for CP, T, and CPT without exchanging the right-handed and left-handed representative components that form a Dirac spinor, as is done in the traditional Dirac formalism. Then, we discuss some salient aspects of the discrete symmetries within quantum field theory (QFT). Besides the generic discussion, we also consider aspects arising within specific renormalizable theories, such as Quantum Electrodynamics (QED) and Yang-Mills (YM) theory. With the above, in addition to presenting a good introduction for non-experts, we establish how to use the chiral fermion formalism to study discrete symmetries in the context of QFT.

hep-th↗

arXiv2025

CPT Symmetry and Its Breaking in the Chiral Fermion Formalism

In this paper, we review the fundamental aspects of ${\cal N} = 1$ supergravity (SUGRA) and employ the chiral formalism to describe spin-$\frac{3}{2}$ fermions. Armed with this, we analyze the discrete symmetries of the graviton in the context of linearized gravity (LG) and Rarita-Schwinger (RS) fields, which include the description of the gravitino. Additionally, we highlight the advantages of the chiral formalism in classifying Lorentz and CPT-violating terms in RS theories, extending these models by including Lorentz-violating operators, as has been done in LG.

hep-th↗

arXiv2023

Signatures of Dipolar Dark Matter on Indirect Detection

In this work we study the annihilation of fermionic dark matter, considering it as a neutral particle with non-vanishing magnetic ($M$) and electric ($D$) dipole moments. Effective cross section of the process $χ\overlineχ \rightarrow γγ$ is computed starting from a general form of the coupling $χ\overlineχ γ$ in the framework of an extension of the Standard Model. By taking into account the annihilation of dark matter pairs into mono-energetic photons, we found that for masses of $O(10^2)$ GeV, an electric dipole moment $\sim 10^{-16}\, \textrm{e cm}$ is required to satisfy the current relic density inferences. Additionally, in order to pin down models viable to describe the physics of dark matter in the early Universe, we also constrain our model according to recent measurements of the temperature anisotropies of the cosmic microwave background radiation, and report constraints to the electric and magnetic dipole moments for a range of masses within our model.

hep-ph↗

arXiv2021

Does an accelerated mirror suffer hindrance from vacuum?

We study the accelerated motion of mirrors and the photonic Unruh effect. The solutions of Maxwell's equations with appropriate boundary conditions in Rindler coordinates are found. The canonical quantization of the field is carried out properly. Important consequences arise from the presence of mirrors or polarizers. It is shown that a single reflective surface produces frequency quantization due to Dirichlet conditions applied to the $-1/(αx)^2$ anomalous potential for non-inertial observers. The number of photons per accelerated mode is estimated via Hankel functions.

gr-qc↗

arXiv2018

Diffraction of particles in free fall

The problem of a beam of quantum particles falling through a diffractive screen is studied. The solutions for single and double slits are obtained explicitly when the potential is approximated by a linear function. It is found that the resulting patterns depend on a quasi-time $τ$ given by a function of the coordinate along the propagation axis in a classical combination $z_0-t^2 F/m$, while the diffraction effects along transverse axes are due solely to $m/\hbar$. The consequences on the precision at which the equivalence principle can be tested are discussed. Realizations with ultra cold neutrons, Bose-Einstein condensates and molecular beams are proposed.

quant-ph↗

arXiv2018

Searching for LFV Flavon decays at hadron colliders

The search for Flavons with a mass of $\mathcal{O}$(1) TeV at current and future colliders might probe low-scale flavor models. We are interested in the simplest model that invokes the Froggatt-Nielsen (FN) mechanism with an Abelian flavor symmetry, which includes a Higgs doublet and a FN complex singlet. Assuming a CP conserving scalar potential, there are a $CP$-even $H_F$ and a $CP$-odd $A_F$ Flavons with lepton flavor violating (LFV) couplings. The former can mix with the standard-model-like Higgs boson, thereby inducing tree-level LFV Higgs interactions that may be at the reach of the LHC. We study the constraints on the parameter space of the model from low-energy LFV processes, which are then used to evaluate the Flavon decay widths and the $gg\to ϕ\to τμ$ ($ϕ=H_F,\,A_F$) production cross section at hadron colliders. After imposing several kinematic cuts to reduce the SM main background, we find that for $m_{H_F}$ about 200-350 GeV, the decay $H_F \to τμ$ might be at the reach of the LHC for a luminosity in the range 1-3 ab$^{-1}$, however, a luminosity of the order of 10 ab$^{-1}$ would be required to detect the $A_F \to τμ$ decay. On the other hand a future 100 TeV $pp$ collider could probe masses as high as $\mathcal{O}$(10) TeV if it reaches an integrated luminosity of at least 20 ab$^{-1}$. Therefore, the 100 TeV Collider could work as a Flavon factory.

hep-ph↗

arXiv2017

A bottom-up approach to the strong CP problem

The strong CP problem is one of many puzzles in the theoretical description of elementary particle physics that still lacks an explanation. While top-down solutions to that problem usually comprise new symmetries or fields or both, we want to present a rather bottom-up perspective. The main problem seems to be how to achieve small CP violation in the strong interactions despite large CP violation in weak interactions. Observation of CP violation is exclusively through the Higgs--Yukawa interactions. In this paper, we show that with minimal assumptions on the structure of mass (Yukawa) matrices they do not contribute to the strong CP problem and thus we can provide a pathway to a solution of the strong CP problem within the structures of the Standard Model and no extension at the electroweak scale is needed. However, to address the flavor puzzle, models based on minimal SU(3) flavor groups leading to the proposed flavor matrices are favored. Though we refrain from an explicit a UV completion of the Standard Model, we provide a simple requirement those models should have to intrinsically not show a strong CP problem.

hep-ph↗

arXiv2010

Electroweak right-handed neutrinos and new signals at the LHC

We explore in detail the Higgs phenomenology that results in a model where right-handed neutrinos have a mass scale of the order of the electroweak scale. In this model all scales arise from spontaneous symmetry breaking, and this is achieved with a Higgs sector that includes an extra Higgs singlet in addition to the standard model Higgs doublet. The scalar spectrum includes two neutral CP-even states ($h$ and $H$ with $m_{h} < m_{H}$)and a neutral CP-odd state ($σ$) that can be identified as a pseudo-Majoron. The parameter of the Higgs potential are constrained using a perturbativity criteria. Higgs BR and cross-sections are discussed, with special emphasis on the detection at the LHC.

hep-ph↗

arXiv2009

Yukawa txtures and charged Higgs boson phenomenology in the type-III two-Higgs-doublet model

We discuss the implications of assuming a four-zero Yukawa texture for the properties of the charged Higgs boson within the context of the general 2-Higgs Doublet Model of Type III. We begin by presenting a detailed analysis of the charged Higgs boson couplings with heavy quarks and the resulting pattern for its decays. The production of charged Higgs bosons is also sensitive to the modifications of its couplings, so that we also evaluate the resulting effects on the top decay $t \to b H^{+}$ as well as on `direct' $c\bar{b}\to H^++c. c.$ and `indirect' $q\bar q,gg\to \bar t b H^++c. c.$ production. Significant scope exists at the Large Hadron Collider for several $H^\pm$ production and decay channels combined to enable one to distinguish between such a model and alternative 2-Higgs doublet scenarios.

hep-ph↗

arXiv2006

Comment to ``Quantization of FRW spacetimes in the presence of a cosmological constant and radiation''

The quantization of the Friedmann-Robertson-Walker spacetime in the presence of a negative cosmological constant was used in a recent paper to conclude that there are solutions that avoid singularities (big bang--big crunch) at the quantum level. We show that a proper study of their model{\sl does not prevent} the occurrence of singularities at the quantum level, in fact the quantum probability of such event is larger than the classical one. Our numerical simulations based on the powerful variational sinc collocation method (VSCM) also show that the precision of the results of that paper is much lower than the 20 significant digits reported by the authors.

gr-qc↗