Seesaw tau lepton mass and calculable neutrino masses in a 3-3-1 model

Abstract

In this work we show that in a version of the 3-3-1 model proposed by Duong and Ma, in which the introduction of a scalar sextet is avoided by adding a singlet heavy charged lepton, the lepton gains mass through a seesawlike mechanism. We also show how to generate neutrino masses at the one-loop level, and give the respective Maki-Nakagawa-Sakata mixing matrices for a set of the parameters. We also consider the effect of adding a singlet right-handed neutrino. DOI: 10.1103/PhysRevD.65.093017 PACS number͑s͒: 12.15.Ff, 12.60.Cn, 14.60.Fg, 14.60.Pq Some years ago a model with SU(3) C SU(3) L U(1) N gauge symmetry was proposed, 3-3-1 for short, in which the three lepton families transform in the same way under the gauge symmetry, i.e., ⌿ aL ϭ( a ,l a ,l a c ) L ϳ(1,3,0) with a ϭe,, ͓1,2͔. Therefore, in this model the lepton mass term transforms as (1,3,0) (1,3,0)ϭ(1,3*,0) A (1,6,0) S ; hence, in order to give mass to the charged leptons it is possible to introduce a triplet ϭ(and a symmetric sextet Sϳ(1,6,0) ͓2͔. With the triplet only, one of the charged leptons remains massless and the other two are mass degenerate. Hence, at least a sextet S has to be introduced in order to give arbitrary masses to all charged leptons. Although this implies that the model has a rather complicated Higgs scalar sector, it is interesting to stress that all the extensions of the electroweak standard model with extra Higgs scalar multiplets, such as multiHiggs doublets ͓3͔, singlets ͓4,5͔, and triplets ͓6͔, are embedded in this 3-3-1 model. In fact, under the subgroup SU(2) L U(1) Y ʚSU(3) L U(1) N the model has three scalar doublets, four singlets ͑one neutral, one singly charged, and two doubly charged͒, and a complex triplet. This sort of model also gives some insight into the family replication and into the observed value of the weak mixing angle sin 2 W Ͻ1/4. Moreover, recently the 3-3-1 models have become interesting possibilities for explaining the new value of the positive muon anomalous magnetic moment, reported by the Muon (gϪ2) Collaboration ͓7͔. The new (gϪ2) value is consistent not only with supersymmetry ͓8͔ but also with several versions of the 3-3-1 model as was shown in Ref. ͓9͔. Finally, in one version of the model it is possible to generate the top and bottom quark masses at the tree level while the other quarks and charged leptons gain mass at the one-loop level ͓10͔.The seesaw mechanism was proposed in order to understand the smallness of the neutrino masses ͓11͔. On the other hand, later, a generalization of this mechanism was introduced, which is also valid for the charged lepton masses, in the context of the minimal left-right symmetric model ͓12,13͔. Here we will show, in a 3-3-1 model, that a similar mechanism can be implemented for the case of the lepton mass and that the three neutrinos gain mass radiatively. In the case of three neutrinos the masses and mixing are almost completely determined by the charged lepton parameters. In fact, they depend only upon a coupling constant () of a quartic term of the...

Charged fermion masses with Yukawa coupling strength universality

“…Models for neutrino masses generation in the 3-3-1 model are discussed in several papers [13,14]. We show that our scheme can be compatible with the one of the Ref.…”

Gauge vectors and double beta decay

“…There are two simple possibilities to generate a realistic charged lepton spectrum. One of them is to introduce a vector-like pair of singlet charged fermions [48,49]. We will call this version of the model PPF-E.…”

Lepton number violation in 331 models

“…7 That the wrong prediction for the charged lepton spectrum in the PPF model can be cured using vector-like leptons was noted already in [69,70].…”

“…We have found that several of the originally proposed 331 models can not explain correctly the observed neutrino masses (nor charged lepton masses, in one case). Thus, it is necessary to extend these models and we present several possible modifications that can bring these models in agreement with experimental data, some of which have already been considered before [14,[66][67][68][69][70]. We focus here (mostly) on neutrino masses and mixings and leave aside other LNV processes, which we mention only briefly when it is relevant.…”