Search

We will study in details the full scalar potential of the Minimal Supersymmetric $SU(3)_{C}\times SU(3)_{L}\times U(1)_{N}$ Model when all the scalars fields belong to sextet and anti-sextet representation obtain VEV. We will present numerical predictions for neutral scalars of this model, we will show that the mass of the light scalar of CP par is $125.5$ GeV while the light pseudoscalar have mass bigger than $150$ GeV., Comment: 19 pages, 1 table, 5 figures

The future detection of gravitational waves (GWs) from a galactic core-collapse supernova will provide information on the physics inside protoneutron stars (PNS). In this work, we apply three different classification methods for the PNS non-radial oscillation modes: Cowling classification, Generalized Cowling Nomenclature (GCN), and a Classification Based on Modal Properties (CBMP). Using PNS models from $3$D simulations of core-collapse supernovae, we find that in the early stages of the PNS evolution, typically before $0.4$ seconds after the bounce, the Cowling classification is inconsistent, but the GCN and the CBMP provide complementary information that helps to understand the evolution of the modes. In the GCN, we note several avoided crossings as the mode frequencies evolve at early times, while the CBMP tracks the modes across the avoided crossings. We verify that the strongest emission of GWs by the PNS corresponds to the $f$-mode in the GCN, indicating that the mode trapping region alternates between the core and the envelope at each avoided crossing. At later times, approximately $0.4$ seconds after the bounce, the three classification methods present a similar description of the mode spectrum. We use our results to test universal relations for the PNS modes according to their classification and find that the behaviour of the universal relations for $f$- and $p$-modes is remarkably simple in the CBMP., Comment: 11 pages, 8 figures. Matches the version accepted on MNRAS

In this article, we present a detailed study of the masses of all gauge bosons, as well as explaing recent experimental data regarding the $W$-boson mass presented by the CDF collaboration and even possible changes that these data can bring to experimental measurements of the masses of $Z$-boson mass in the context of the Minimal Supersymmetric $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{N}$ Model. We also intend to show a phenomenological analysis of possible mixtures of gauge bosons in this model. We will show that our numerical predictions for the masses of the physical gauge bosons are within the current experimental limits., Comment: 31 pages, 6 figures and 6 Tables

In this lectures, we give a review about the Minimal Supersymmetric Standard Model (MSSM) with $R$-Parity Violation because it provides an attractive way to generate neutrino masses, lepton mixing angles in acconcordance to present neutrino data., Comment: 17 pages, 1 figure

We will study in details the full scalar potential of the Minimal Supersymmetric $SU(3)_{C}\times SU(3)_{L}\times U(1)_{N}$ Model. We will present numerical predictions for all the usual scalars of this model, we will show that the mass of the light scalar of CP par is $125.5$ GeV, such that its masses satisfy the current experimental constraints., Comment: 22 pages, 10 figures, it was made to present at 6th ComHEP: Colombian Meeting on High Energy Physics but I forget to submitt it but I have finnished it I am put my review here and I hope I can present it in some conference

We will present within the context of the supersymmetric models with $SU(3)_{C}\times SU(2)_{L}\times U(1)_{Y^\prime}\times U(1)_{B-L}$ gauge symmetry an explanation for the new data on the $W$-boson mass recently presented by the CDF collaboration. We will also study the neutral boson sector of this model., Comment: 29 pages, 15 figures and 7 tables, it was made to present at 6th ComHEP, last year, and in Dark Matter but I forget to submit it but I have finnish it I am put my review here and I hope I can present it in some conference, it is is the continuation of arXiv:2209.04653 [hep-ph] but now the new VEV contributes to the masses of fermions

We build a supersymmetric model with $SU(2)_{L}\otimes SU(2)_{R}\otimes U(1)_{(B-L)}$ electroweak gauge symmetry, where $SU(2)_{L}$ is the left-handed currents while $SU(2)_{R}$ is the right-handed currents and $B$ and $L$ are the usual baryonic and leptonic numbers. We can generate an universal seesaw mechanism to get masses for all the usual fermions in this model, it means quarks and leptons, and also explain the mixing experimental data. We will also to study the masses of the Gauge Bosons and also the masses of all usual scalars of this model., Comment: 33 pages, 5 tables and 12 figures

Neutron stars are the densest objects in the Universe, with $M \sim 1.4 M_{\odot}$ and $R \sim 12$ km, and the equation of state associated to their internal composition is still unknown. The extreme conditions to which matter is subjected inside neutron stars could lead to a phase transition in their inner cores, giving rise to a hybrid compact object. The observation of $2M_{\odot}$ binary pulsars (PSR~J1614-2230, PSR~J0343$+$0432 and PSR~J0740$+$6620) strongly constraints theoretical models of the equation of state. Moreover, the detection of gravitational waves emitted during the binary neutron star merger, GW170817, and its electromagnetic counterpart, GRB170817A, impose additional constraints on the tidal deformability. In this work, we investigate hybrid stars with sequential phase transitions hadron-quark-quark in their cores. We assume that both phase transitions are sharp and analyse the rapid and slow phase conversion scenarios. For the outer core, we use modern hadronic equations of state. For the inner core we employ the constant speed of sound parametrization for quark matter. We analyze more than 3000 hybrid equations of state, taking into account the recent observational constraints from neutron stars. The effects of hadron-quark-quark phase transitions on the normal oscillation modes $f$ and $g$, are studied under the Cowling relativistic approximation. Our results show that, in the slow conversion regime, a second quark-quark phase transition gives rise to a new $g_2$~mode. We discuss the observational implications of our results associated to the gravitational waves detection and the possibility of detecting hints of sequential phase transitions and the associated $g_2$~mode., Comment: 24 pages, 9 figures

We consider an Supersymmetric extension of the Standard Model with some extra Higgs doublets and a global $(B - L)$, where $B$ and $L$ are the usual baryonic and lepton number respectivelly, and ${\cal Z}_{3} \otimes {\cal Z}^{\prime}_{3}$ symmetries of the non-SUSY model presented at [1].., Comment: 26 pages, 2 figures and 9 Tables

We consider an extension of the standard electroweak model with three Higgs doublets and global $B-L$ and $\mathbb{Z}_2$ symmetries. Two of the scalar doublets are inert due to the $\mathbb{Z}_2$ symmetry. We calculated all the mass spectra in the scalar and lepton sectors and accommodate the leptonic mixing matrix as well. We also include an analysis of the scalar sector, showing that the potential is limited from below, and we obtain the masses of the scalar sector. Furthermore we consider the effects of the model on the anaomalous magnetic dipole of charged leptons and the $\mu\to e\gamma$ decay. We also present the SUSY version of the model with global $B-L$., Comment: 18 pages, 7 figures, corrected typos. arXiv admin note: text overlap with arXiv:1705.01009

We review very nice mechanism to generate masses to all the neutrinos in the Minimal Supersymmetric Standard Model (MSSM) without break $R$-parity. In consequence we get viable axion as Dark Matter candidate and at the same time solve the $\mu$-problem in a similar way as done in the Next to Minimal Supersymmetric Model (NMSSM)., Comment: 9 pages and 1 figure

We build a supersymmetric version with $SU(3)_{C}\otimes SU(2)_{L}\otimes U(1)_{Y^{\prime}}\otimes U(1)_{(B-L)}$ gauge symmetry, where $Y^{\prime}$ is a new charge and ($B$) and ($L$) are the usual baryonic and leptonic numbers, respectivelly. The model has three right-handed neutrinos with non identical $(B-L)$ charges. We will use the superfield formalism in order to build our lagrangian and it is possible to accommodate all fermion masses at the tree level. In particular, the type-I seesaw mechanism is implemented for the generation of the active neutrino masses and also explain the mixing angle at the fermion sector. There are good candidates to Dark Matter, it can be the lighest righ-handed neutrinos or lighest right-handed sneutrinos or the lighest usual scalar field and due a Majorana phase at sneutrinos right-handed masses, it can induce Leptogenesis in this model., Comment: 417 pages, 3 tables and 6 figures. arXiv admin note: substantial text overlap with arXiv:2003.04638

We give a review about the Minimal Supersymmetric Standard Model with three right-handed neutrinos (MSSM3RHN). We, first introduce the minimal set of fields to built this model in their superfields formalism. After it, we build the lagrangian of the model in the superspace formalism and also introduce the soft terms to break SUSY. We show how to get masses to the neutrinos and sneutrinos in this model., Comment: 47 pages, 3 tables and 10 figures

In this lectures, we give a review about the Minimal Supersymmetric Standard Model (MSSM) and the General Singlet Extensions of the MSSM (GSEMSSM). We, first introduce the minimal set of fields to built both models. Then we introduce their superfields and using them we build the lagrangian of those models in the superspace formalism. We show how to get the mass spectrum of those model in the $R$-parity scenarios and we also show how to get some Feynman Rules with the Gauge Bosons., Comment: 54 pages, 22 figures, 8 tables. arXiv admin note: text overlap with arXiv:hep-ph/9903257, arXiv:hep-ph/0606288, arXiv:1205.5081, arXiv:hep-ph/9611409, arXiv:hep-ph/0012288 by other authors

We study the Dynamical Casimir Effect (DCE) due to an Abelian gauge field in 2+1 dimensions, in the presence of semitransparent, zero-width mirrors, which may move or deform in a time-dependent way. We obtain general expressions for the probability of motion-induced pair creation, which we render in a more explicit form, for some relevant states of motion., Comment: 14 pages, no figures

We consider a model with three Higgs doublet in a discrete $B - L\times \mathbb{Z}_3$ discrete symmetries. Two of the scalar doublets are inert due to the $\mathbb{Z}_3$ symmetry. We calculated all the mass spectra in the scalar and lepton sectors and accommodate the leptonic mixing matrix as well., Comment: Superseded by arXiv:2007.14788

We build a supersymmetric version with $SU(3)_C\otimes SU(2)_L\otimes U(1)_{Y^\prime}\otimes U(1)_{B-L}$ gauge symmetry, where $Y^\prime$ is a new charge and $B$ and $L$ are the usual baryonic and leptonic numbers. The model has three right-handed neutrinos with identical $B-L$ charges, and can accommodate all fermion masses at the tree level. In particular, the type-I seesaw mechanism is implemented for the generation of the active neutrino masses. We obtain the mass spectra of all sectors and for the scalar one we also give the flat directions allowed by the model., Comment: Version submitted for publication. 29 pages

In this paper, we give a brief review of the Minimal Supersymmetric Standard Model (MSSM) and "$\mu$ from $\nu$" Supersymmetric Standard Model ($\mu \nu$SSM). Then we propose a generalization of $\mu \nu$SSM in order to explain the recent ATLAS, CMS and LHCb results. This "new" $\mu \nu$SSM generalizes the superpotential $W_{suppot}$ of $\mu \nu$SSM by including two terms that generate a mixing among leptons, gauginos and higgsinos while keeping the charginos and neutralinos masses unchanged. Also, it is potentially interesting for cosmological applications as it displays flat directions of the superpotential and a viable leptogenesis mechanism., Comment: 21 pages. arXiv admin note: text overlap with arXiv:hep-ph/0311336 by other authors

We build an supersymmetric version of the minimal 3-3-1 model with just two Higgs triplets using the superfield formalism. We study the mass spectrum of all particles in concordance with the experimental bounds. At the tree level, the masses of charged gauge bosons are the same as those of charged Higgs bosons. We also show that the electron, muon and their neutrinos as well as down and strange quarks gain mass through the loop correction. The narrow constraint on the ratio t_w = \frac{w}{w^\prime} is given by studying the new invisible decay mode of the Z boson., Comment: Journal version, 4 pictures are added for more details in explanation the generating masses of leptons

The R-symmetry formalism is applied for the supersymmetric economical SU(3)_C X SU(3)_L X U(1)_X (3-3-1) model. The generalization of the minimal supersymmetric standard model relation among R-parity, spin and matter parity is derived, and discrete symmetries for the proton stability in this model are imposed. We show that in such a case it is able to give leptons masses at just the tree level. A simple mechanism for the mass generation of the neutrinos is explored. With the new R-parity, the neutral fermions get mass matrix with two distinct sectors: one light which is identified with neutrino mass matrix, another heavy one which is identified with neutralinos one. The similar situation exists in the charged fermion sector. Some phenomenological consequences such as proton stability, neutrinoless double beta decays are discussed., Comment: 18 pages, 4 figures, the reference [40] was added upon the arXiv admin note

This review starts out with a brief history of the photino-gluino phenomenology. Next, it describes difficulties encountered in the construction of Feynman amplitudes when dealing with Majorana fermions and outlines a procedure that circumvents this difficulty by means of a prescription based on a well-defined fermion flow without explicit charge-conjugation matrices at the vertex equations. Finally, as an illustration, it calculates the cross section for the production of photinos and gluinos., Comment: 31 pages, 10 figures, 1 table; To appear in Volume 43 of the Brazilian Journal of Physics

In this article we investigate the influence of nuclear effects in the production of gluinos in nuclear collisions at the LHC, and estimate the transverse momentum dependence of the nuclear ratios $R_{pA} = {\frac{d\sigma (pA)}{dy d^2 p_T}} / A {\frac{d\sigma (pp)}{dy d^2 p_T}}$ and $R_{AA} = {\frac{d\sigma (AA)}{dy d^2 p_T}} / A^2 {\frac{d\sigma (pp)}{dy d^2 p_T}}$. We demonstrate that depending on the magnitude of the nuclear effects, the production of gluinos could be enhanced, compared to proton-proton collisions. The study of these observables can be useful to determine the magnitude of the shadowing and antishadowing effects in the nuclear gluon distribution. Moreover, we test different SPS scenarios, corresponding to different soft SUSY breaking mechanisms, and find that the nuclear ratios are strongly dependent on that choice., Comment: 7 pages, 5 figures; results and discussions changed/added. Accepted for publication in Physical Review C

We consider the minimal supersymmetric extension of the 3-3-1 model. We study the mass spectra of this model in the fermionic and gauge bosons sectors without the antisextet. We also present some phenomenological consequences of this model at colliders such as Large Hadron Collider (LHC) and International Linear Collider(ILC)., Comment: 39 pages, 3 Tables and 9 figures

We recall the many obstacles which seemed, long ago, to prevent supersymmetry from possibly being a fundamental symmetry of Nature. We also present their solutions, leading to the construction of the supersymmetric extensions of the Standard Model. Finally we discuss briefly the early experimental searches for Supersymmetry., Comment: 40 pages, 10 figures, 3 Tables

Gluinos are expected to be one of the most massive sparticles (supersymmetric partners of usual particles) which constitute the Minimal Supersymmetric Standard Model (MSSM). The gluinos are the partners of the gluons and they are color octet fermions, due this fact they can not mix with the other particles. Therefore in several scenarios, given at SPS convention, they are the most massive particles and their nature is a Majorana fermion. Therefore their production is only feasible at a very energetic machine such as the Large Hadron Collider (LHC). Being the fermion partners of the gluons, their role and interactions are directly related with the properties of the supersymmetric QCD (sQCD). We review the mechanisms for producing gluinos at the LHC and investigate the total cross section and differential distributions, making an analysis of their uncertainties, such as the gluino and squark masses, as obtained in several scenarios, commenting on the possibilities of discriminating among them., Comment: 4 pages, 4 figures, 1 table, presented at II Latin American Workshop on High Energy Phenomenology, December 3-7, 2007, Sao Miguel das Missoes, Brazil

In this article we review the mechanisms in several supersymmetric models for producing gluinos at the LHC and its potential for discovering them. We focus on the MSSM and its left-right extensions. We study in detail the strong sector of both models. Moreover, we obtain the total cross section and differential distributions. We also make an analysis of their uncertainties, such as the gluino and squark masses, which are related to the soft SUSY breaking parameters., Comment: 34 pages, 10 figures, 2 tables; Introduction expanded, appendices suppressed, conclusions unchanged

In a previous work we have showed that the ${\cal Z}_{2}^{\prime}$ Symmetry, imply that the light fermions, the electron and the quarks, $u,d$ and $s$, get their masses only at one loop level. Here, we considere the more general hypothesis for flavour mixing in the sfermion sector in the MSSM. Then, we present our results to the masses of these light fermions and as a final result we can explain why the $s$ quark is heavier than the $u,d$ quarks. This mechanism is in agrement with the experimental constraint on the sfermion's masses values., Comment: 22 pages, 8 figures, TeX mistakes corrected, accepted for publication in JHEP

On this article we show explicity that Supersymmetric Left-Right Models already satisfy the R-parity. They also respect $L$-parity and $B$-parity., Comment: 9 pages

We point out the production of the charginos and neutralinos in electron-electron process in several supersymmetric models, in order to show that the International Linear Collider can discover double charged charginos if these particles really exist in nature., Comment: 9 pages, 9 figures, Talk given at CTP symposium on Supersymmetry at LHC: Theoretical and Experimental Perspectives, The British University in Egypt, Cairo, Egypt, 11-14 March 2007

The supersymmetric extension of the economical 3-3-1 model is presented. The constraint equations and the gauge boson identification establish a relation between the vacuum expectation values (VEVs) at the top and bottom elements of the Higgs triplet $\chi$ and its supersymmetric counterpart $\chi^\prime$. Because of this relation, the exact diagonalization of neutral gauge boson sector has been performed. The gauge bosons and their associated Goldstone ones mix in the same way as in non-supersymmetric version. This is also correct in the case of gauginos. The eigenvalues and eigenstates in the Higgs sector are derived. The model contains a heavy neutral Higgs boson with mass equal to those of the neutral non-Hermitian gauge boson $X^0$ and a charged scalar with mass equal to those of the $W$ boson in the standard model, i. e. $ m_{\varrho_1} = m_W$. This result is in good agreement with the present estimation: $m_{H^\pm} > 79.3$ GeV, CL= 95 %. We also show that the boson sector and the fermion sector gain masses in the same way as in the non-supersymmetric case., Comment: 33 pages

We build the complete supersymmetric version of a 3-4-1 gauge model using the superfield formalism. We point out that a discrete symmetry, similar to the R-symmetry in the minimal supersymmetric standard model, is possible to be defined in this model. Hence we have both R-conserving and R-violating possibilities. We also discuss some phenomenological results coming from this model., Comment: 23 pages, 2 figures and 1table

The R-symmetry formalism is applied for the supersymmetric SU(3)_C X SU(3)_L X U(1)_X (3-3-1) model with right-handed neutrinos. For this kind of models, we study generalization of the MSSM relation among R-parity, spin and matter-parity. Discrete symmetries for the proton stable in this model are imposed, and we show that in such a case it is able to give leptons masses at only the tree level contributions required. A simple mechanism for the mass generation of the neutrinos is explored. We show that at the low-energy effective theory, neutrino spectrum contains three Dirac fermions, one massless and two degenerate in mass. At the energy-level where the mixing among them with neutralinos turned on, neutrinos obtain Majorana masses and correct the low-energy effective result which naturally gives rise to an inverted hierarchy mass pattern. This mass spectrum can fit the current data with minor fine-tuning. Consistent values for masses of the charged leptons are also given. In this model, the MSSM neutralinos and charginos can be explicitly identified in terms of the new constraints on masses which is not as in a supersymmetric version of the minimal 3-3-1 model., Comment: 25 pages

We consider the mass generation for the usual quarks and leptons in some supersymmetric models. The masses of the top, the bottom, the charm, the tau and the muon are given at the tree level. All the other quarks and the electron get their masses at the one loop level in the Minimal Supersymmetric Standard Model (MSSM) and in two Supersymmetric Left-Right Models, one model uses triplets (SUSYLRT) to break $SU(2)_{R}$-symmetry and the other use doublets(SUSYLRD)., Comment: 24 pages, 2 figures and 3 tables

We consider a model with soft CP violation which accommodate the CP violation in the neutral kaons even if we assume that the Cabibbo-Kobayashi-Maskawa mixing matrix is real and the sources of CP violation are three complex vacuum expectation values and a trilinear coupling in the scalar potential. We show that for some reasonable values of the masses and other parameters the model allows to explain all the observed CP violation processes in the $K^0$-$\bar{K}^0$ system., Comment: 19 pages, RevTeX 4. Minor modifications

We consider the minimal supersymmetric extension of the 3-3-1 model and we study the mass spectra in the scalar sector of this model without the anti-sextet. We show that all our lighest scalars are in agreement with the experimental limits., Comment: It was included on the introduction of the article the motivation to > study the model, and we moved the sections 4.1 and 4.2 to the appendix. It has 22 pages, 9 figures. It was accepted to be published at International Journal of Modern Physics A

We investigate a scalar sector of the supersymmetric $ SU_C(3) \otimes SU_L(3)\otimes U_N(1)$ model with right-handed neutrinos. The mass spectra are derived. We show that only neutral Higgs sector with lepton number L=0 could have a VEV. There is no mixing between scalars having L=0 and bilepton scalars having L=2. There are six Goldstone bosons: two in neutral sector, three in pseudo-scalar sector and one in charged scalar sector. For a given set of input parameters (five from the $F$ terms and two from the soft term) all the scalar sectors in this model contain the upper limit of 230 GeV to the mass of the lightest scalar, which are in agreement with the lower limit of the SM Higgs boson obtained by LEP., Comment: 26 pages, 12 figures

The aim of this paper is to discuss what sort of baryon-number violating process arise on the supersymmetric versions of the model based on the gauge group $SU(3)_C}\otimes SU(3)_{L}\otimes U(1)_{N}$. We discuss the mechanism of baryon number violation which induces proton decay, and derive bounds on the relevant couplings., Comment: 17 pages, 9 figures. submited to European Physical Journal

We consider the supersymmetric extension of the 3-3-1 model with right-handed neutrinos. We study the mass spectra in the scalar and pseudoscalar sectors, and for a given set of the input parameters, we find that the lightest scalar in the model has a mass of 130 GeV and the lightest pseudoscalar has mass of 5 GeV. However, this pseudoscalar decouples from the $Z^0$ at high energy scales since it is almost a singlet under $SU(2)_L\otimes U(1)_Y$., Comment: Revtex4, 16 pages, no figures

The goal of this article is to outline the advantages of the measurement of left-right asymmetries in lepton-lepton ($l^{-}l^{-}\to l^{-}l^{-}$) scattering for performing precision measurements of $\sin^2 \theta_W$ and the discovery of ``new physics''., Comment: RevTeX, 6 pages and one .eps figure. Based on contribution to XXII Encontro Nacional de Fisica de Particulas e Campos, October 22--26, Sao Lourenco (MG), Brazil. One typo corrected and a new reference included

We consider the mass generation for both charginos and neutralinos in a 3-3-1 supersymmetric model. We show that R-parity breaking interactions leave the electron and one of the neutrinos massless at the tree level. However the same interactions induce masses for these particles at the 1-loop level. Unlike the similar situation in the MSSM the masses of the neutralinos are related to the masses of the charginos., Comment: RevTex, 11 pages incluing 2 .eps figures. Extended published version

Foi com base neste estudo que fizemos a constru\c{c}\~ao da vers\~ao supersim\'etrica dos modelos de simetria $SU(3)_{C} \otimes SU(3)_{L} \otimes U(1)_{N}$ \cite{susy331}, apresentado no final da minha tese de doutorado \cite{mcr1}. Bem como dos estudos fenomenol\'ogicos subsequente \cite{mcr}., Comment: 67 p\'aginas, 4 tabelas e 3 figuras

The goal of this article is to derive the Feynman rules involving charginos, neutralinos, double charged gauge bosons and sleptons in a 3-3-1 supersymmetric model. Using these Feynman rules we will calculate the production of a double charged chargino with a neutralino and also the production of a pair of single charged charginos, both in an electron- electron $e^-e^-$ process., Comment: 18 pages, 8 figures, 2 tables

We build the complete supersymmetric version of a 3-3-1 gauge model using the superfield formalism. We point out that a discrete symmetry, similar to the R-symmetry in the minimal supersymmetric standard model, is possible to be defined in this model. Hence we have both R-conserving and R-violating possibilities. Analysis of the mass spectrum of the neutral real scalar fields shown that in this model the lightest scalar Higgs has a mass upper limit, and at the tree level it is 124.5 GeV for a given illustrative set of parameters., Comment: RevTex, extended and revised version, 20 pages, one eps figure

By considering left-right (L-R) asymmetries we study the capabilities of lepton colliders in searching for new exotic vector bosons. Specifically we study the effect of a doubly charged bilepton boson and an extra neutral vector boson appearing in a 3-3-1 model on the L-R asymmetries for the processes $e^-e^-\to e^-e^-$, $\mu^-\mu^-\to\mu^-\mu^-$ and $e^-\mu^-\to e^-\mu^-$ and show that these asymmetries are very sensitive to these new contributions and that they are in fact powerful tools for discovery this sort of vector bosons., Comment: RevTeX, 22 pages, 12 eps figures

Several left-right parity violating asymmetries in lepton-lepton scattering in fixed target and collider experiments are considered as signals for doubly charged vector bosons (bileptons)., Comment: Revtex, 7 pages, one .eps figure. Contribution to the VIII Mexican School of Particles and Fields, Oaxaca de Ju\'arez, Oax, M\'exico, November 20--29, 1998

We consider, in the electroweak standard model context, several left-right asymmetries in $\mu e$ elastic scattering at fixed target and collider experiments. For the former case, we show that the muon mass effects are important in a wide energy range. We also show that these asymmetries are sensitive to the electroweak mixing angle $\theta_W$. The effect of an extra $Z'$ neutral vector boson appearing in a 331 model is also considered. The capabilities of these asymmetries in the search of this extra $Z'$ are addressed., Comment: RevTeX, 9 pages, 5 gif figures