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Register a new userKinetic mixing effect in the 3-3-1-1 model
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We show that the mixing effect of the neutral gauge bosons in the 3-3-1-1 model comes from two sources. The first one is due to the 3-3-1-1 gauge symmetry breaking as usual, whereas the second one results from the kinetic mixing between the gauge bosons of U(1)_X and U(1)_N groups, which are used to determine the electric charge and baryon minus lepton numbers, respectively. Such mixings modify the rho-parameter and the known couplings of Z with fermions. The constraints that arise from flavor-changing neutral currents due to the gauge boson mixings and non-universal fermion generations are also given.
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In the minimal 3-3-1 model charged leptons come in a non-diagonal 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.
A simple extension of the Standard Model (SM), based on the gauge group $SU(3)_Cotimes SU(3)_Lotimes U(1)_Y$ with $Y$ being the hypercharge, is considered. We show that, by imposing an approximate global $SU(2)_Ltimes SU(2)_R$ custodial symmetry at the SM energy scale, the $Z-Z$ mixing is absent at tree level and the value of the $rho$ parameter can be kept close to one. Tree-level flavor-changing neutral currents are also reduced to three particles, namely $Z$, a CP-odd Higgs and a CP-even Higgs. The model predicts new leptons with electric charges of $pm 1/2e$ and new quarks with $pm 1/6e$ charges as well as new gauge and scalar bosons with $pm 1/2e$ charges. Electric charge conservation requires that one of them must be stable. Their masses are unfortunately free parameters.
We present the features of the fully flipped 3-3-1-1 model and show that this model leads to dark matter candidates naturally. We study two dark matter scenarios corresponding to the triplet fermion and singlet scalar candidates, and we determine the viable parameter regimes constrained from the observed relic density and direct detection experiments.
We show that the economical 3-3-1 model poses a very high new physics scale of the order of 1000~TeV due to the constraint on the flavor-changing neutral current. The implications of the model for neutrino masses, inflation, leptogenesis, and superheavy dark matter are newly recognized. Alternatively, we modify the model by rearranging the third quark generation differently from the first two quark generations, as well as changing the scalar sector. The resultant model now predicts a consistent new physics at TeV scale unlike the previous case and may be fully probed at the current colliders. Particularly, due to the minimal particle contents, the models under consideration manifestly accommodate dark matter candidates and neutrino masses, with novel and distinct production mechanisms. The large flavor-changing neutral currents that come from the ordinary and exotic quark mixings can be avoided due to the approximate $B-L$ symmetry.
We show that in the minimal 3-3-1 model the flavor changing neutral currents (FCNCs) do not impose necessarily strong constraints on the mass of the $Z^prime$ of the model if we also consider the neutral scalar contributions to such processes, like the neutral mesons mass difference and rare semileptonic decays. We first obtain numerical values for all the mixing matrices of the model i.e., the unitary matrices that rotate the left- and right-handed quarks in each charge sector which give the correct mass of all the quarks and the CKM mixing matrix. Then, we find that there is a range of parameters in which the neutral scalar contributions to these processes may interfere with those of the $Z^prime$, implying this vector boson may be lighter than it has been thought.
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