We propose a new non-universal U (1) ′ extension of the standard model with the addition of three exotic quark singlets, two scalar singlets and one additional scalar doublet. We obtain family dependent couplings with a new Z ′ boson in the quark sector and universal couplings with the lepton sector. From experimental data on Z ′ research at CERN-LHC collider, we find limit regions in the U (1) ′ free parameters (Z ′ mass and coupling constant), which we use to obtain total decay width and invariantmass distributions. By introducing discrete symmetries and mixing couplings between ordinary and exotic fermions, we obtain predictable mass relations in the quark sector compatible with the phenomenological values without large fine tuning of the Yukawa couplings and with few free parameters, where hierarchies between quark families can be understood from the existence of heavy beyond standard model particles.

In the framework of a nonuniversal Uð1Þ 0 extension of the standard model, we propose a scalar candidate for cold dark matter which exhibits interactions with ordinary matter through Higgs and gauge bosons. Using limits from low energy observables, we find constraints on the new physics parameters of the model associated to the extra Abelian symmetry, especially the mass of the additional neutral gauge boson Z 0 and the new gauge coupling constant. We find that for the lower experimental limit M Z 0 ¼ 3 TeV constrained by direct research at LHC, the ratio between the Uð1Þ 0 and SUð2Þ L gauge coupling constants is around 0.4. Taking into account this limit and the observable relic density of the Universe, we search for new constraints on the mass of the dark matter particle of the model. We find that for a Higgsphobic model, the mass of the scalar dark matter must be M σ ¼ 70 GeV. We also find different kinematical threshold and resonances that enhance the dispersion of dark matter into ordinary matter for different regions of the space of parameters of the model, obtaining masses as low as 1.3 GeV and as large as 125 GeV without allowed intermediate regions due to resonances.

We explore constraints on the scalar coupling in a family nonuniversal U (1) extension of the standard model free from anomalies with a complex scalar dark matter particle. From unitarity and stability of the Higgs potential, we find the full set of bounds and order relations for the scalar coupling constants. Using recent data from the CERN-LHC collider, we study the signal strenght of the diphoton Higgs decay, which imposes very stringent bounds to the scalar couplings and other scalar parameters, including parameters associated to the dark matter. Taking into account these constraints, the observable relic density of the Universe, and the limits from LUX collaboration for direct detection, we obtain allowed masses for the dark matter particle as low as 55 GeV. By assuming that the lightest scalar boson of the model corresponds to the observed Higgs boson, we evaluate deviations from the SM of the trilineal Higgs self-coupling. The conditions from unitarity, stability and Higgs diphoton decay data allow trilineal deviations in the range 0 ≤

We propose a model based on the SU (3) C ⊗ SU (3) L ⊗ U (1) X gauge symmetry with an extra S 3 ⊗ Z 2 ⊗ Z 4 ⊗ Z 12 discrete group, which successfully accounts for the SM quark mass and mixing pattern. The observed hierarchy of the SM quark masses and quark mixing matrix elements arises from the Z 4 and Z 12 symmetries, which are broken at a very high scale by the SU (3) L scalar singlets (σ ,ζ ) and τ , charged under these symmetries, respectively. The Cabbibo mixing arises from the down-type quark sector whereas the up quark sector generates the remaining quark mixing angles. The obtained magnitudes of the CKM matrix elements, the CP violating phase, and the Jarlskog invariant are in agreement with the experimental data.

Flavor changing neutral currents arise in the SU (3) c ⊗SU (4) L ⊗U (1) X extension of the standard model because anomaly cancellation among the fermion families requires one generation of quarks to transform differently from the other two under the gauge group. In the weak basis the distinction between quark families is meaningless. However, in the mass eigenstates basis, the CabibboKobayashi-Maskawa mixing matrix motivates us to classify left-handed quarks in families. In this sense there are, in principle, three different assignments of quark weak eigenstates into mass eigenstates. In this work, by using measurements at the Z-pole, atomic parity violation data and experimental input from neutral meson mixing, we examine two different models without exotic electric charges based on the 3-4-1 symmetry, and address the effects of quark family nonuniversality on the bounds on the mixing angle between two of the neutral currents present in the models and on the mass scales M Z 2 and M Z 3 of the new neutral gauge bosons predicted by the theory. The heaviest family of quarks must transform differently in order to keep lower bounds on M Z 2 and M Z 3 as low as possible without violating experimental constraints.