arXiv subjects

A. E. Cárcamo Hernández

Publications and source records attributed to A. E. Cárcamo Hernández.

At least 73 records · Page 4Linked to original sources

arXiv2020

Fermion masses and mixings and some phenomenological aspects of a 3-3-1 model with linear seesaw mechanism

We propose a viable theory based on the $SU(3)_C\times SU(3)_L\times U(1)_X$ gauge group supplemented by the $S_4$ discrete group together with other various symmetries, whose spontaneous breaking gives rise to the current SM fermion mass and mixing hierarchy. In the proposed theory the small light active neutrino masses are generated from a linear seesaw mechanism mediated by three Majorana neutrinos. The model is capable of reproducing the experimental values of the physical observables of both quark and lepton sectors. Our model is predictive in the quark sector having 9 effective parameters that allow to successfully reproduce the four CKM parameters and the six Standard Model (SM) quark masses. In the SM quark sector, there is particular scenario, motivated by naturalness arguments, which allows a good fit for its ten observables, with only six effective parameters. We also study the single heavy scalar production via gluon fusion mechanism at proton-proton collider. Our model is also consistent with the experimental constraints arising from the Higgs diphoton decay rate.

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arXiv2020

Low scale type I seesaw model for lepton masses and mixings

In contrast to the original type I seesaw mechanism that requires right-handed Majorana neutrinos at energies much higher than the electroweak scale, the so-called low scale seesaw models allow lighter masses for the additional neutrinos. Here we propose an alternative low scale type I seesaw model, where neither linear nor inverse seesaw mechanisms take place, but the spontaneous breaking of a discrete symmetry at an energy scale much lower than the model cutoff is responsible for the smallness of the light active neutrino masses. In this scenario, the model is defined with minimal particle content, where the right-handed Majorana neutrinos can have masses at the $\sim 50\mbox{ GeV}$ scale. The model is predictive in the neutrino sector having only four effective parameters that allow to successfully reproduce the experimental values of the six low energy neutrino observables.

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arXiv2019

A 3-3-1 model with low scale seesaw mechanisms

We construct a viable 3-3-1 model with two $SU(3)_L$ scalar triplets, extended fermion and scalar spectrum, based on the $T^{\prime}$ family symmetry and other auxiliary cyclic symmetries, whose spontaneous breaking yields the observed pattern of SM fermion mass spectrum and fermionic mixing parameters. In our model the SM quarks lighter than the top quark, get their masses from a low scale Universal seesaw mechanism, the SM charged lepton masses are produced by a Froggatt-Nielsen mechanism and the small light active neutrino masses are generated from an inverse seesaw mechanism. The model is consistent with the low energy SM fermion flavor data and successfully accommodates the current Higgs diphoton decay rate and predicts charged lepton flavor violating decays within the reach of the forthcoming experiments.

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arXiv2019

Radiative type-I seesaw neutrino masses

We discuss a radiative type-I seesaw. In these models, the radiative generation of Dirac neutrino masses allows to explain the smallness of the observed neutrino mass scale for rather light right-handed neutrino masses in a type-I seesaw. We first present the general idea in a model independent way. This allows us to estimate the typical scale of right-handed neutrino mass as a function of the number of loops. We then present two example models, one at one-loop and another one at two-loop, in which we discuss neutrino masses and lepton flavour violating constraints in more detail. For the two-loop example, right-handed neutrino masses must lie below 100 GeV, thus making this class of models testable in heavy neutral lepton searches.

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arXiv2019

Comment on the article by D. Borah and B. Karmakar "Linear seesaw for Dirac neutrinos with A4 flavour symmetry", Phys. Lett. B789 (2019) 59-70, arXiv: 1806.10685

D. Borah and B. Karmakar in Phys. Lett. B789 (2019) have proposed an A4 flavoured linear seesaw model to realise light Dirac neutrinos. In this comment article, we show that some neutrino Yukawa interactions were missed in the model, thus implying that a different formula would be needed to determine the effective neutrino mass matrix, with significantly different results. Our result shows that, unlike stated in Phys. Lett. B789 (2019), that the inverted neutrino mass spectrum is not ruled out.

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arXiv2019

Generating lepton masses and mixings with a heavy vector doublet

We construct two viable extensions of the SM with a heavy vector in the fundamental $SU\left( 2\right) _{L}$ representation and nine SM singlet scalar fields, consistent with the current SM fermion mass spectrum and fermionic mixing parameters. The small masses for the active neutrinos are generated from radiative seesaw mechanism at one loop level mediated by the neutral components of the heavy vector as well as by the left handed Majorana neutrinos. The proposed models predicts rates for charged lepton flavor violating processes within the reach of the forthcoming experiments.

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arXiv2019

Fermion Mass and Mixing in a Low-Scale Seesaw Model based on the S4 Flavor Symmetry

We construct a low-scale seesaw model to generate the masses of active neutrinos based on $S_4$ flavor symmetry supplemented by the $Z_2 \times Z_3 \times Z_4 \times Z_{14}\times U(1)_L$ group, capable of reproducing the low energy Standard model (SM) fermion flavor data. The masses of the SM fermions and the fermionic mixings parameters are generated from a Froggatt-Nielsen mechanism after the spontaneous breaking of the $S_4\times Z_2 \times Z_3 \times Z_4 \times Z_{14}\times U(1)_L$ group. The obtained values for the physical observables of the quark and lepton sectors are in good agreement with the most recent experimental data. The leptonic Dirac CP violating phase $\de _{CP}$ is predicted to be $259.579^\circ$ and the predictions for the absolute neutrino masses in the model can also saturate the recent constraints.

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arXiv2019

Viable low-scale model with Universal and Inverse Seesaw Mechanisms

We formulate a viable low-scale seesaw model, where the masses for the standard model (SM) charged fermions lighter than the top quark emerge from a universal seesaw mechanism mediated by charged vectorlike fermions. The small light active neutrino masses are produced from an inverse seesaw mechanism mediated by right-handed Majorana neutrinos. Our model is based on the $A_{4} $ family symmetry, supplemented by cyclic symmetries, whose spontaneous breaking produces the observed pattern of SM fermion masses and mixings. The model can accommodate the muon and electron anomalous magnetic dipole moments and predicts strongly suppressed $μ\rightarrow eγ$ and $τ\rightarrow μγ$ decay rates, but allows a $τ\rightarrow eγ$ decay within the reach of the forthcoming experiments.

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arXiv2019

Phenomenology of an extended IDM with loop-generated fermion mass hierarchies

We perform a comprehensive analysis of the most distinctive and important phenomenological implications of the recently proposed mechanism of sequential loop generation of strong hierarchies in the Standard Model (SM) fermion mass spectra. This mechanism is consistently realized at the level of renormalizable interactions in an extended variant of the Inert Higgs Doublet model, possessing the additional $Z_{2}^{(1)}\times Z_{2}^{(2)}$ discrete and $U_{1X}$ gauge family symmetries, while the matter sectors of the SM are extended by means of $SU_{2L}$-singlet scalars, heavy vector-like leptons and quarks, as well as right-handed neutrinos. We thoroughly analyze the most stringent constraints on the model parameter space, coming from the $Z^{\prime }$ collider searches, related to the anomaly in lepton universality, and the muon anomalous magnetic moment, as well as provide benchmark points for further tests of the model and discuss possible "standard candle" signatures relevant for future explorations.

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arXiv2019

Sequentially loop-generated quark and lepton mass hierarchies in an extended Inert Higgs Doublet model

Extended scalar and fermion sectors offer new opportunities for generating the observed strong hierarchies in the fermion mass and mixing patterns of the Standard Model (SM). In this work, we elaborate on the prospects of a particular extension of the Inert Higgs doublet model where the SM hierarchies are generated sequentially by radiative virtual corrections in a fully renormalisable way, i.e. without adding any non-renormalisable Yukawa terms or soft-breaking operators to the scalar potential. Our model has a potential to explain the recently observed $R_{K}$ and $R_{K^{\ast }}$ anomalies, thanks to the non universal $U_{1X}$ assignments of the fermionic fields that yield non universal $Z^{\prime}$ couplings to fermions. We explicitly demonstrate the power of this model for generating the realistic quark, lepton and neutrino mass spectra. In particular, we show that due to the presence of both continuous and discrete family symmetries in the considered framework, the top quark acquires a tree-level mass, lighter quarks and leptons get their masses at one- and two-loop order, while neutrino masses are generated at three-loop level. The minimal field content, particle spectra and scalar potential of this model are discussed in detail.

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arXiv2019

Higgs and gauge boson phenomenology of the 3-3-1 model with CKS mechanism

We perform a comprehensive analysis of several phenomenological aspects of the renormalizable extension of the inert 3-3-1 model with sequentially loop-generated SM fermion mass hierarchy. Special attention is paid to the study of the constraints arising from the experimental data on the $ρ$ parameter, as well as those ones resulting from the charged lepton flavor violating process $μ\to eγ$ and dark matter. We also study the single $Z'$ production via Drell-Yan mechanism at the LHC. We have found that $Z'$ gauge bosons heavier than about $4$ TeV comply with the experimental constraints on the oblique $ρ$ parameter as well as with the collider constraints. In addition, we have found that the constraint on the charged lepton flavor violating decay $μ\rightarrow eγ$ sets the sterile neutrino masses to be lighter than about $1.12$ TeV. In addition the model allows charged lepton flavor violating processes within reach of the forthcoming experiments. The scalar potential and the gauge sector of the model are analyzed and discussed in detail. Our model successfully accommodates the observed Dark matter relic density.

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arXiv2019

A highly predictive $A_{4}$ flavour 3-3-1 model with radiative inverse seesaw mechanism

We build a highly predictive 3-3-1 model, where the field content is extended by including several $SU(3)_{L}$ scalar singlets and six right handed Majorana neutrinos. In our model the $SU(3)_{C}\times SU\left( 3\right) _{L}\times U\left( 1\right) _{X}$ gauge symmetry is supplemented by the $A_{4}\times Z_{4}\times Z_{6}\times Z_{16}\times Z_{16}^{\prime }$ discrete group, which allows to get a very good description of the low energy fermion flavor data. In the model under consideration, the $A_{4}\times Z_{4}\times Z_{6}\times Z_{16}\times Z_{16}^{\prime }$ discrete group is broken at very high energy scale down to the preserved $Z_{2}$ discrete symmetry, thus generating the observed pattern of SM fermion masses and mixing angles and allowing the implementation of the loop level inverse seesaw mechanism for the generation of the light active neutrino masses, respectively. The obtained values for the physical observables in the quark sector agree with the experimental data, whereas those ones for the lepton sector also do, only for the case of inverted neutrino mass spectrum. The normal neutrino mass hierarchy scenario of the model is ruled out by the neutrino oscillation experimental data. We find an effective Majorana neutrino mass parameter of neutrinoless double beta decay of $% m_{ee}=46.9$ meV, a leptonic Dirac CP violating phase of $-81.37^{\circ}$ and a Jarlskog invariant of about $10^{-2}$ for the inverted neutrino mass hierarchy. The preserved $Z_{2}$ symmetry allows for a stable scalar dark matter candidate.

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arXiv2019

Neutrino predictions from a left-right symmetric flavored extension of the standard model

We propose a left-right symmetric electroweak extension of the Standard Model based on the $Δ\left( 27\right)$ family symmetry. The masses of all electrically charged Standard Model fermions lighter than the top quark are induced by a Universal Seesaw mechanism mediated by exotic fermions. The top quark is the only Standard Model fermion to get mass directly from a tree level renormalizable Yukawa interaction, while neutrinos are unique in that they get calculable radiative masses through a low-scale seesaw mechanism. The scheme has generalized $μ-τ$ symmetry and leads to a restricted range of neutrino oscillations parameters, with a nonzero neutrinoless double beta decay amplitude lying at the upper ranges generically associated to normal and inverted neutrino mass ordering.

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arXiv2019

Muon anomalies and the $SU(5)$ Yukawa relations

We show that, within the framework of $SU(5)$ Grand Unified Theories (GUTs), multiple vector-like families at the GUT scale which transform under a gauged $U(1)'$ (under which the three chiral families are neutral) can result in a single vector-like family at low energies which can induce non-universal and flavourful $Z'$ couplings, which can account for the B physics anomalies in $R_{K^{(*)}}$. In such theories, we show that the same muon couplings which explain $R_{K^{(*)}}$ also correct the Yukawa relation $Y_e=Y_d^T$ in the muon sector without the need for higher Higgs representations. To illustrate the mechanism, we construct a concrete a model based on $SU(5)\times A_4 \times Z_3\times Z_7$ with two vector-like families at the GUT scale, and two right-handed neutrinos, leading to a successful fit to quark and lepton (including neutrino) masses, mixing angles and CP phases, where the constraints from lepton flavour violation require $Y_e$ to be diagonal.

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arXiv2019

$Δ\left( 27\right)$ flavor singlet-triplet Higgs model for fermion masses and mixings

We propose a multiscalar singlet extension of the singlet-triplet Higgs model capable of explaining the SM fermion mass spectrum and mixing parameters. Our model is based on the $Δ\left( 27\right) $ family symmetry, supplemented by cyclic symmetries, which are spontaneously broken thus yielding the observed hierarchy of the SM charged fermion masses and quark mixing angles. The masses of the light active neutrinos are produced by type-II seesaw mechanism mediated by the neutral component of the $SU(2)_{L}$ scalar triplet. The model symmetries lead to the extended Gatto-Sartori-Tonin relations between the quark masses and mixing angles.

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arXiv2018

Lepton masses and mixings in a $T'$ flavoured 3-3-1 model with type I and II seesaw mechanisms

We propose a renormalizable $T'$ flavor model based on the $SU(3)_C\times SU(3)_L\times U(1)_X\times U(1)_{\mathcal{L}}$ gauge symmetry, consistent with the observed pattern of lepton masses and mixings. The small masses of the light active neutrinos are produced from an interplay of type I and type II seesaw mechanisms, which are induced by three heavy right-handed Majorana neutrinos and three $SU(3)_L$ scalar antisextets, respectively. Our model is only viable for the scenario of normal neutrino mass hierarchy, where the obtained physical observables of the lepton sector are highly consistent with the current neutrino oscillation experimental data. In addition, our model also predicts an effective Majorana neutrino mass parameter of $m_β \sim 1.41541\times 10^{-2}$ eV, a Jarlskog invariant of the order of $J_{CP}\sim -0.032$ and a leptonic Dirac CP violating phase of $\de = 238^\circ$, which is inside the $1σ$ experimentally allowed range.

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arXiv2018

The first $Δ(27)$ flavor 3-3-1 model with low scale seesaw mechanism

We propose a viable model based on the $SU(3)_C\times SU(3)_L\times U(1)_X$ gauge group, augmented by the $U(1)_{L_g}$ global lepton number symmetry and the $Δ(27) \times Z_3\times Z_{16}$ discrete group, capable of explaining the Standard Model (SM) fermion masses and mixings, and having a low scale seesaw mechanism which can be tested at the LHC. In addition the model provides an explanation for the SM fermion masses and mixings. In the proposed model, small masses for the light active neutrinos are generated by an inverse seesaw mechanism caused by non renormalizable Yukawa operators and mediated by three very light Majorana neutrinos and the observed hierarchy of the SM fermion masses and mixing angles is produced by the spontaneous breaking of the $Δ(27) \times Z_{3}\times Z_{16}$ symmetry at very large energy scale. This neutrino mass generation mechanism is not presented in our previous 3-3-1 models with $Δ(27)$ group (Nucl.Phys. B913 (2016) 792-814 and Eur.Phys.J. C76 (2016) no.5, 242), where the masses of the light active neutrinos arise from a combination of type I and type II seesaw mechanisms (Nucl.Phys. B913 (2016) 792-814) as well as from a double seesaw mechanism (Eur.Phys.J. C76 (2016) no.5, 242). Thus, this work corresponds to the first implementation of the $Δ(27)$ symmetry in a 3-3-1 model with low scale seesaw mechanism.

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arXiv2018

A variant of 3-3-1 model for the generation of the SM fermion mass and mixing pattern

We propose an extension of the 3-3-1 model with an additional symmetry group $Z_{2}\times Z_{4} \times U(1)_{L_g}$ and an extended scalar sector. To our best knowledge this is the first example of a renormalizable 3-3-1 model, which allows explanation of the SM fermion mass hierarchy by a sequential loop suppression: tree-level top and exotic fermion masses, 1-loop bottom, charm, tau and muon masses; 2-loop masses for the light up, down, strange quarks as well as for the electron. The light active neutrino masses are generated from a combination of linear and inverse seesaw mechanisms at two loop level. The model also has viable fermionic and scalar dark matter candidates.

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