Search

In 3-3-1 models, anomaly cancellation requires that one of the three families of quarks transforms as triplet by SU 3 L , with the other two transforming necessarily as anti-triplet. This is an important feature of the model because, with it, we explain family replication. Thus it is mandatory to discriminate which of the families will transform as triplet by SU 3 L because the main consequence of anomaly cancellation in 3-3-1 models is the arising of processes violating flavor at the tree level by means of neutral currents mediated by gauge and scalar fields, and each case leads to different results. In this work, we consider the 3-3-1 model with right-handed neutrinos. Among the spectrum of 3-3-1 particles that contribute to the flavor changing neutral processes, there is a pseudoscalar that may be the lightest of the 3-3-1 particles, and this then should give the main contribution to such processes. We then calculate its contribution to the K 0 − K ¯ 0 mixing transition and confront it with the current experimental results. We do this for the three cases in which one of the family of quarks transforms as a triplet by SU 3 L . According to our findings, each case leads to different constraints on the mass of the pseudoscalar, and the case in which the third family of quarks transforms as triplet seems to be the favoured one. We also obtain the most stringent bounds on the mass of the pseudoscalar of the model. [ABSTRACT FROM AUTHOR]

In this work we introduce scalar leptoquarks into the 3-3-1 model with right-handed neutrinos with the aim of solving the (g − 2) μ puzzle. We show that besides the model supports leptoquarks in the octet, sextet, triplet and singlet representations, we identified that only one specif leptoquark in the singlet representation leads to flip of chirality as required to generate positive and robust contribution to the (g − 2) μ. Then we calculate its contributions to (g − 2) μ and to the decay process μ → e γ and discuss the results. [ABSTRACT FROM AUTHOR]

In the 3-3-1 model with right-handed neutrinos (331RHNs), three triplets of scalars engender the correct sequence of symmetry breaking, S U (3) C × S U (3) L × U (1) X → S U (3) C × S U (2) L × U (1) Y → S U (3) C × U (1) EM , generating mass for all fermions, except neutrinos. Tiny neutrino masses may be achieved by implementing the type II seesaw mechanism into the model, requiring the addition of one sextet of scalars to the original scalar content. As consequence, it emerges a very complex scalar sector, involving terms that violate lepton number explicitly, too. The main obstacle to the development of the phenomenology of such scenario is the knowledge of its spectrum of scalars since, now, there are 15 massive scalar particles on it. The proposal of this work is to do an exhaustive analysis of such scalar sector with lepton number being explicitly violated at low, electroweak and high energy scales by means of trilinear terms in the potential. The first case can be addressed analytically and, as a nice result, we have observed that the scalar content of such case is split into two categories: One belonging to the 331 energy scale and the other belonging to the EWSB energy scale, with the last recovering the well know 2THDM + triplet. For the other cases, the scalar sector can be addressed only numerically. Hence, we proposed a very general approach for the numerical study of the potential, avoiding simplifications that can make us reach conclusions without foundation. We show that, in the case of lepton number being explicitly violated at electroweak scale, it is possible to recover the same physics of the 2HDM + triplet, as the previous case. Among all the possibilities, we call the attention to one special case which generates the 3HDM+triplet scenario. For the last case, when lepton number is violated at high energy scale, the sextet becomes very massive and decouples from the original scalar content of the 3-3-1 model. We also discuss, when possible, the phenomenological aspects of each case. [ABSTRACT FROM AUTHOR]

The advent of the LHC, and the proposal of building future colliders as the ILC, both programmed to explore new physics at the TeV scale, justify the recent interest in collider phenomenology of seesaw mechanisms whose signatures lie on TeV scale or less. The most popular TeV scale seesaw mechanisms are the inverse seesaw ones. There are three types of inverse seesaw mechanisms, but only that one implemented in an arrangement involving six non-standard heavy neutrinos has received attention. In this paper we develop an inverse seesaw mechanism based on Higgs triplet model and simulate its collider phenomenology by producing doubly charged Higgses at the LHC and ILC and analyzing their subsequent decays in pair of leptons. We find that although the new scalars decouple from the standard ones, signals of these scalars may be detected in the current run of the LHC or in the future ILC. Our simulations probe the model in the region of parameter space that generates the correct neutrino masses and mixing for both normal and inverted hierarchy cases. [ABSTRACT FROM AUTHOR]

We discuss a model where a mixed warm and hot keV neutrino dark matter rises naturally. We arrange active and sterile neutrinos in the same SU(3)L multiplet, with the lightest sterile neutrino being dark matter. The other two heavy sterile neutrinos, through their out-of-equilibrium decay, contribute both to the dilution of dark matter density and its population, after freeze-out. We show that this model features all ingredients to overcome the overproduction of keV neutrino dark matter, and explore the phenomenological implications for Big Bang Nucleosynthesis and the number of relativistic degrees of freedom. [ABSTRACT FROM AUTHOR]

Seesaw mechanisms are the simplest and the most elegant way of generating small masses for the active neutrinos (m ν). In these mechanisms m ν is inversely proportional to the lepton number breaking scale (M) that, in the particular case of the type I seesaw mechanism, is the Majorana mass of the right-handed neutrinos. In the canonical case right-handed neutrinos are supposed to be heavy belonging to the GUT scale. With the advent of the LHC people began to suppose these neutrinos having mass at TeV scale. In this case very tiny Yukawa couplings are required. As far as we know there are no constraints on the energy scales associated to the seesaw mechanisms. In what concern 3-3-1 models, when we trigger the type I seesaw mechanism the lepton number breaking scale that suppresses active neutrino masses contributes to the masses of the standard gauge bosons. Current data on m W demands the mechanism to be performed at GeV scale. As main implication we may have right handed neutrinos with mass varying from few keVs up to hundreds of GeVs. We also investigate the viability of the mechanism and found as interesting result that in the case in which the right-handed neutrino masses belong to the range keV-MeV scale, viability of the mechanism demands that the lightest of the right-handed neutrinos be stable, which makes of it a natural dark matter candidate, and that the lightest of the active neutrinos be ultralight. [ABSTRACT FROM AUTHOR]

Since the heavy neutrinos of the inverse seesaw mechanism mix largely with the standard ones, the charged currents formed with them and the muons have the potential of generating robust and positive contribution to the anomalous magnetic moment of the muon. However, bounds from the non-unitary in the leptonic mixing matrix may restrict so severely the parameters of the mechanism that, depending on the framework under which the mechanism is implemented, may render it unable to explain the recent muon g-2 result. In this paper we show that this happens when we implement the mechanism into the standard model and into two versions of the 3-3-1 models. [ABSTRACT FROM AUTHOR]

In this work we consider scenarios where light sterile neutrinos are mixed with the active ones. The active-sterile neutrino mixings render new contributions to the invisible Z decay width which will depend predominantly on the active-sterile mixing matrix elements. We then use the current experimental value of the invisible Z decay width to obtain bounds on these mixing matrix elements for both (3+1) and (3+2) models. [ABSTRACT FROM AUTHOR]

Abstract: In this work we show that light right-handed neutrinos, with mass in the sub-eV scale, is a natural outcome in a 3–3–1 model. By considering effective dimension five operators, the model predicts three light right-handed neutrinos, weakly mixed with the left-handed ones. We show also that the model is able to explain the LSND experiment and still be in agreement with solar and atmospheric data for neutrino oscillation. [Copyright &y& Elsevier]

In the minimal 3-3-1 model charged leptons come in a nondiagonal basis. Moreover, the Yukawa interactions of the model lead to a non-hermitian charged lepton mass matrix. In other words, the minimal 3-3-1 model presents a very complex lepton mixing. In view of this we check rigorously if the possible textures of the lepton mass matrices allowed by the minimal 3-3-1 model can lead or not to the neutrino mixing required by the recent experiments in neutrino oscillation. [ABSTRACT FROM AUTHOR]

In models with flat extra dimensions tiny Dirac neutrino masses can be generated via the coupling of four-dimensional Standard Model fields to a higher dimensional fermion. Here we argue that, in spite of the Dirac nature of the neutrino, quantization of the electric charge can still be understood as a result of anomaly cancellation, charge conservation and naturalness requirements. [ABSTRACT FROM AUTHOR]

The MiniBooNE collaboration recently released a report claiming have observed an excess of electron and anti-electron neutrino with significance of 4.8 σ C.L. corroborating, in this way, the long-standing LSND anomaly. Combined LSND and MiniBooNE analysis reach a significance of 6.0 σ C.L. Such a result, if confirmed by future experiments, will cause considerable impact on particle physics since that such anomalies, when interpreted in terms of neutrino oscillation, require the existence of at least one light sterile neutrino. It happens that, on according to standard scenarios, such light sterile neutrino is incompatible with current cosmological data. In this way, understand these anomalies requires an extension of the standard model capable of generating tiny masses for both active and sterile neutrinos and re-conciliates such a result with cosmology. An interesting proposal in this direction involves the existence of a secret sector interacting exclusively with sterile neutrinos. In this work we implement the canonical seesaw mechanism into the standard model in such a way that generates tiny masses to the active and sterile neutrinos and embody a secret sector capable of re-conciliating eV sterile neutrinos with cosmology. As other gains, the scalar content required by the implementation of the mechanism provides contribution to rare lepton decays, may accommodate the g − 2 of the muon and poses a scalar singlet that may drive inflation through Higgs inflation mechanism without problem with loss of unitarity. [ABSTRACT FROM AUTHOR]

Theoretical consistency of the 3-3-1 model with right-handed neutrinos demands that the number of family of fermions be exactly equal to three. In this brief report we show that such theoretical requirement results in a clean and severe bound on the Z–Z′ mixing angle: -3.979×10-3<ϕ<1.309×10-4 with 90% CL. [ABSTRACT FROM AUTHOR]

We implement the seesaw mechanism in the 3-3-1 model with right-handed neutrinos. This will be accomplished by the introduction of a scalar sextet into the model and the spontaneous violation of lepton number. The main result of this work is that the seesaw mechanism can work already at the TeV scale with the consequence that the right-handed neutrino masses lie in the electroweak scale, in the range from MeV to tens of GeV. This window provides a great opportunity to test their appearance at current detectors, though when we contrast our results with some previous analyses concerning the detection sensitivity at LHC, we conclude that further work is needed in order to validate this search. [ABSTRACT FROM AUTHOR]

Inverse seesaw is a genuine TeV scale seesaw mechanism. In it active neutrinos with masses at eV scale requires lepton number be explicitly violated at keV scale and the existence of new physics, in the form of heavy neutrinos, at TeV scale. Therefore it is a phenomenologically viable seesaw mechanism since its signature may be probed at the LHC. Moreover it is successfully embedded into gauge extensions of the standard model as the 3-3-1 model with the right-handed neutrinos. In this work we revisit the implementation of this mechanism into the 3-3-1 model and employ deep learning analysis to probe such setting at the LHC and, as main result, we have that if its signature is not detected in the next LHC running with energy of 14 TeVs, then, the vector boson Z ′ of the 3-3-1 model must be heavier than 4 TeVs. [ABSTRACT FROM AUTHOR]