arXiv subjects

Adrian Palcu

Publications and source records attributed to Adrian Palcu.

At least 19 recordsLinked to original sources

arXiv2022

Weak charges quantization in $SU(3)_{c} \otimes SU(n)_{L} \otimes U(1)_{Y}$ gauge models

After proving, in a previous paper, that the electric charge quantization occurs as a natural consequence in renormalizable $SU(3)_c \otimes SU(n)_{L} \otimes U(1)_{Y}$ gauge models, we take here a step further within the same paradigm in order to obtain the precise weak charges quantization. To this end a viable boson mass spectrum yields first, once a proper parametrization in the Higgs sector is employed. Hence, by diagonalizing the neutral bosons mass matrix, the quantized neutral weak charge operators are obtained. The Standard Model phenomenology is entirely recovered, as its scale ($v_{SM}=246$ GeV) is decoupled from the higher scale ($V\sim$ 10 TeV) specific to our generalized electro-weak unification.

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arXiv2022

Weak charges in $SU(5)_{L} \times U(1)_{Y}$ gauge models

Within the framework of a renormalizable $SU(5)_{L} \times U(1)_{Y}$ electro-weak gauge model with no exotic electric charges, we obtain all the neutral weak charge operators and their quantization, once the diagonalization of the neutral boson mass matrix is properly performed. Our results open up the path to a rich and promising phenomenological outcome. All the Standard Model phenomenology is recovered by simply decoupling the latter's scale ($v_{SM}=246$ GeV) from the higher scale ($V\sim$ 10 TeV) specific to our new electro-weak unification.

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arXiv2021

$SU(5)_{L} \times U(1)_{Y}$ electroweak unification

We propose here - for the first time in the literature, to our best knowledge - an electroweak unification based on the $SU(5)_{L}\times U(1)_{Y}$ gauge group. The spontaneous symmetry breaking takes place in the manner $SU(5)_{L}\times U(1)_{Y} \rightarrow U(1)_{em}$, due to a particular Higgs sector consisting of five scalar quintuplets. Each scalar quintuplet acquires its own vacuum expectation value, by means of a proper parametrization which is worked out once the overall vacuum expectation value in the model is established. The decoupling of the low energy regime (corresponding to the Standard Model) from the high scale (required by out model here) is straightforwardly achieved in order to preserve the consistency with the present experimental data. Finally, a promising phenomenological outcome is derived by simply tuning a single free parameter. Our results include, besides a viable one-parameter mass spectrum, also the prediction of precisely three generations in the fermion sector and the electric charge quantization.

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arXiv2019

On trilinear terms in the scalar potential of 3-3-1 gauge models

The trilinear terms {\normalsize of the form $\sqrt{2} fε^{ijk} ρ_i χ_jϕ_k$} in the scalar potential of a 3-3-1 gauge model are considered. When looking for the eigenbasis of the massive physical Higgs bosons that survive the spontaneous symmetry breakdown of the model -- in light of the observed SM-like Higgs boson with mass $m_{h}\simeq125$ GeV reported in 2012 at the LHC -- one gets a strong constraint to the cubic term. It has to be smaller than usual $f\ll w$, in flagrant contradiction with the large one $f\simeq w$ which is propagated in the literature to date.

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arXiv2015

Implementing inverse seesaw mechanism in SU(3)xSU(4)xU(1) gauge models

Generating appropriate tiny neutrino masses via inverse seesaw mechanism within the framework of a particular SU(3)xSU(4)xU(1) gauge model is the main outcome of this letter. It is achieved by simply adding three singlet exotic Majorana neutrinos to the usual ones included in the three lepton quadruplet representations. The theoretical device of treating gauge models with high symmetries is the general method by Cotaescu. It provides us with a unique free parameter (a) to be tuned in order to get a realistic mass spectrum for the gauge bosons and charged fermions in the model. The overall breaking scale can be set around 1-10 TeV so its phenomenology is quite testable at present facilities.

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arXiv2015

A straightforward realization of a quasi-inverse seesaw mechanism at TeV scale

In this letter we address the issue of generating appropriate tiny neutrino masses within the framework of a particular $SU(3)_{c}\otimes SU(3)_{L}\otimes U(1)_{X}$ gauge model by adding three singlet exotic Majorana neutrinos to the ones included in the three lepton triplet representations. The theoretical device is the general method of treating gauge models with high symmetries $SU(3)_{c}\otimes SU(N)_{L}\otimes U(1)_{X}$ proposed by Cotăescu more than a decade ago. When it is worked-out in the 3-3-1 model it supplies a unique free parameter ($a$) to be tuned in order to get a realistic mass spectrum for both the boson and charged-fermion sectors. Its most appealing feature (of special interest here) is that it contains all the needed ingredients to realize the inverse seesaw mechanism for neutrinos. The mandatory couplings leading to the lepton number soft violation in pure Majorana terms result without invoking any element outside the model (such as GUT scales, as one usually does in the literature). The overall breaking scale in this particular model can be set around 1 TeV so its phenomenology is quite testable at present facilities.

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arXiv2012

Dimension-five effective operators in electro-weak SU(4)xU(1) gauge models

We prove in this paper that the electro-weak SU(4)L x U(1)X gauge models with spontaneous symmetry breaking can offer a natural framework for generating neutrino masses by simply exploiting the tree level realization of dimension-five effective operators. The novelty of our approach resides in the fact that the scalar sector needs not to be enlarged, since these operators are constructed as direct products among scalar multiplets already existing in the model. There is a unique generic matrix for Youkawa couplings in the neutrino sector. The charged leptons are already in their diagonal basis. This framework can lead to a suitable fit of the established phenomenology for the left-handed neutrinos, while the right-handed neutrino masses come out in the sub-keV region, independently of the cut-off. The latter introduces in the theory an intermediate scale (however, more close to GUT than to SM) at about 10^12GeV which is a crucial ingredient for the left-handed neutrino phenomenology.

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arXiv2011

The Higgs sector of a 3-3-1 model with right-handed neutrinos to be tested at the LHC

We explore in this paper certain phenomenological consequences - to be tested at the LHC - regarding the scalar sector of a SU(3)xSU(3)xU(1) gauge model with right-handed neutrinos. Our analysis is performed in a particular theoretical approach of treating gauge models with spontaneous symmetry breaking in which a single free parameter 'a' finally remains to be tuned, once all the Standard Model phenomenology is recovered. It is also proved that this particular method is flexible enough as to accommodate the traditional approach in which three VEVs supply masses for gauge bosons and fermions, while three accompanying neutral scalars survive the SSB and take part in various interactions. Two of them exhibit a hierarchy m(H3) = 2m(H2) with masses below the SM scale 246 GeV (independently of the parameter 'a') and the third one coming out very heavy (depending on 'a'), at a mass comparable to the overall breaking scale . A plausible scenario implying in 1 - 10 TeV is then exploited.

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arXiv2009

Canonical Seesaw Mechanism in Electro-Weak SU(4)L x U(1)Y Models

In this paper we prove that the canonical seesaw mechanism can naturally be implemented in a particular class of electro-weak SU(4)L x U(1)Y gauge models. The resulting neutrino mass spectrum is determined by just tuning a unique free parameter 'a' within the algebraical method of solving gauge models with high symmetries. All the Standard Model phenomenology is preserved, being unaffected by the new physics occuring at a high breaking scale m ~ 10^11GeV.

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arXiv2009

Boson mass spectrum in $SU(4)_L\otimes U(1)_Y$ model with exotic electric charges

The boson mass spectrum of the electro-weak \textbf{$SU(4)_{L}\otimes U(1)_{Y}$} model with exotic electric charges is investigated by using the algebraical approach supplied by the method of exactly solving gauge models with high symmetries. Our approach predicts for the boson sector a one-parameter mass scale to be tuned in order to match the data obtained at LHC, LEP, CDF.

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arXiv2009

Neutral currents in a $SU(4)_{L}\otimes U(1)_{Y}$ gauge model with exotic electric charges

The weak currents with respect to the diagonal neutral bosons $Z$,$Z^{\prime}$, and $Z^{\prime\prime}$ of a specific \textbf{$SU(4)_{L}\otimes U(1)_{Y}$} gauge model are computed in detail for all the fermion families involved therein. Our algebraical approach, which is based on the general method of solving gauge models with high symmetries proposed several years ago by Cotăescu, recovers in a non-trivial way all the Standard Model values for current couplings of the traditional leptons and quarks, and predicts plausible values for those of the exotic fermions in the model.

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arXiv2009

Electro-weak $SU(4)_L\otimes U(1)_Y$ models without exotic electric charges

For the particular class of \textbf{$SU(4)_{L}\otimes U(1)_{Y}$} electro-weak models without exotic electric charges, some plausible phenomenological predictions - such as the boson mass spectrum and charges of all the fermions involved therein - are made by using the algebraical approach of the exactly solving method for gauge models with high symmetries. Along with the one-parameter resulting mass scale (to be confirmed at TeV scale in LHC, LEP, CDF and other high energy experiments) our approach predicts the exact expressions of the charges (both electric and neutral) in the fermion sector, while all the Standard Model phenomenology is naturally recovered.

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arXiv2009

The Electric Charge Assignment in $SU(4)_{L}\otimes U(1)_{Y}$ Gauge Models

In this brief report, apart from the usual approach, we discriminate among models in the class of \textbf{$SU(4)_{L}\otimes U(1)_{Y}$} electro-weak gauge models by just setting the versors in the method of the exactly solving gauge models with high symmetries. We prove that the method itself naturally predicts the correct assingment of the electric charge spectrum along with the relation between the gauge couplings of the groups involved therein for each particular model in this class.

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arXiv2008

Neutrino Masses with a Suitable Parametrization in the PPF 3-3-1 Gauge Model

Plausible phenomenological consequences of the well-known Pisano-Pleitez- Frampton 3-3-1 model - such as the neutrino masses - are analyzed within the solution provided by the exact algebraical approach - proposed several years ago by Cotaescu - for gauge models with high symmetries. We prove that a suitable parametrisation in the Higgs sector and a redefinition of the three scalar triplets involved therein can lead to realistic predictions for the lepton mass spectrum, while a minimal number of coupling parameters are employed in the Yukawa sector.

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arXiv2008

Charges and Mass Spectrum in the Pisano-Pleitez-Frampton 3-3-1 Gauge Model

The Pisano-Pleitez-Frampton 3-3-1 model is revisited here within the framework of the general method for solving gauge models with high symmetries. This exact algebraical approach - proposed several years ago by one of us - was designed to include a minimal Higgs mechanism that spontaneously breaks the gauge symmetry up to the universal $U(1)_{em}$ electromagnetic one and, consequently, to supply the mass spectrum and the couplings of the currents for all the particles in the model. We prove in this paper that this powerful tool, when is applied to the PPF 3-3-1 model, naturally recovers the whole Standard Model phenomenology and, in addition, predicts - since a proper parametrization is employed - viable results such as: (i) the exact expressions for the boson and fermion masses, (ii) the couplings of the charged and neutral currents and (iii) a plausible neutrino mass pattern. A generalized Weinberg transformation is implemented, while the mixing between the neutral bosons $Z$ and $Z^{\prime}$ is performed as a necessary step by the method itself. Some phenomenological consequences are also sketched, including the strange possibility that simultaneously $m(Z)=m(Z^{\prime})$ and $m(W)=m(V)$ hold.

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arXiv2008

Critical Point in a 3-3-1 Model with Right-Handed Neutrinos

The boson mass spectrum of a 3-3-1 model with right-handed neutrinos is investigated by tuning a unique free parameter whitin the exact algebraical approach for solving gauge models with high symmetries. A very strange coincidence of the masses in both the neutral and the charged boson sectors can occur at a not very high breaking scale. This could explain why the masses of the new bosons have not been exactly weighted in the laboratories by date. In order to have good phenomenological behaviour in the neutrino sector, one can resort to either the conservation of the global lepton number $L_{e}-L_μ-L_τ$ or see-saw mechanism.

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arXiv2007

Charged and Neutral Currents in a 3-3-1 Model with Right-Handed Neutrinos

The charged and the neutral currents are obtained by using a formal algebraical approach (developed and applied by the author) within the exact solution of a 3-3-1 gauge model with right-handed neutrinos. The entire Standard Model phenomenology is recovered without imposing any supplemental condition, but only by choosing an adecquate set of parameters from the very beginning of the calculus. A new and rich phenomenology regarding the particles and their currents occurs as well. The appealing feature of our results resides in the exact expressions of the currents which need not the adjustment usually due to the small mixing angle $ϕ$ between neutral bosons $Z$ and $Z^{\prime}$ (like in the most of the papers in the literature treating the same issue). The required mixing was considered and aleready performed as an intermediate step by the solving method itself, since the physical eigenstates of those bosons were determined and then identified in the neutral currents.

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arXiv2007

The exact eigenstates of the neutrino mass matrix without CP-phase violation

In this paper we obtain the exact mass-eigenstates of the Majorana physical neutrinos. We start by taking into account a general $3\times3$ mass matrix without any CP-phase violation. It is then diagonalized by exactly solving an appropriate set of equations. The solution supplies straightforwardly the mass eigenvalues depending on the diagonal entries and mixing angles. Finally, the consequences of these analytical expressions are discussed assuming various phenomenological restrictions such as conserving the global lepton number $L=L_{e}-L_μ-L_τ$ and the $μ-τ$ interchange symmetry. The minimal absolute mass in the neutrino sector is also obtained since the two plausible scenarios invoked above are employed.

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