FCNC in the 3-3-1 model with right-handed neutrinos

Flavor changing neutral currents coming from a new non-universal neutral Gauge-Boson and from the non-unitary quark mixing matrix for the $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$ model with right handed neutrinos are studied. By imposing as experimental constraints the measured values of the 3x3 quark mixing matrix, the neutral meson mixing, and the bounds measured values for direct flavor changing neutral current processes, the largest mixing of the known quarks with the exotic ones can be established, with new sources of flavor changing neutral currents being identified. Our main result is that for a $|V_{tb}|$ value smaller than one, large rates of rare top decays such as $t\to c\gamma$, $t\to cZ$, and $t\to cg$ (where g stands for the gluon field) are obtained; but if $|V_{tb}|\approx 1$ the model can survive present experimental limits only if the mass of the new neutral Gauge Boson becomes larger that 10 TeV.Comment: 30 pages, 1 figure. Accepted for publication in Phys. Rev.

Five Texture Zeros for Dirac Neutrino Mass Matrices

In this work we propose new five textures zeros for the mass matrices in the lepton sector in order to predict values for the neutrino masses. In our approach we go beyond the Standard Model by assuming Dirac masses for the neutrinos, feature which allows us to make a theoretical prediction for the lightest neutrino mass in the normal ordering. The textures analyzed have enough free parameters to adjust the $V_{\text{\tiny PMNS}}$ mixing matrix including the CP-violating phase, the neutrino mass squared differences $\delta m_{21}^2,\,\delta m_{31}^2$, and the three charged lepton masses. In order to have reliable results two different approaches are used: the first one is based on a least-squares analysis to fit the lepton masses and the mixing parameters to their corresponding experimental values, for this case the best fit for the lightest neutrino mass is $(3.9\pm^{0.6}_{0.8})\times 10^{-3}$ eV.; the second approach is just algebraic, based on the weak basis transformation method, in this case the lightest neutrino mass consistent with the experimental values and the restrictions coming from the five texture zeros of the mass matrices is equal to $(3.5\pm0.9)\times 10^{-3}$ eV

Flipped versions of the universal 3-3-1 and the left-right symmetric models in [SU(3)]3: a comprehensive approach

ABSTRACT: By considering the 3-3-1 and the left-right symmetric models as low energy effective theories of the SU(3)C SU(3)L SU(3)R (for short [SU(3)]3) gauge group, alternative versions of these models are found. The new neutral gauge bosons of the universal 3-3-1 model and its ipped versions are presented; also, the left-right symmetric model and its ipped variants are studied. Our analysis shows that there are two ipped versions of the universal 3-3-1 model, with the particularity that both of them have the same weak charges. For the left-right symmetric model we also found two ipped versions; one of them new in the literature which, unlike those of the 3-3-1, requires a dedicated study of its electroweak properties. For all the models analyzed, the couplings of the Z0 bosons to the standard model fermions are reported. The explicit form of the null space of the vector boson mass matrix for an arbitrary Higgs tensor and gauge group is also presented. In the general framework of the [SU(3)]3 gauge group, and by using the LHC experimental results and EW precision data, limits on the Z0 mass and the mixing angle between Z and the new gauge bosons Z0 are obtained. The general results call for very small mixing angles in the range 10-3 radians and MZ0 > 2.5 TeV

SU(3)c⊗SU(3)L⊗U(1)XSU(3)_c\otimes SU(3)_L\otimes U(1)_X models with four families

In the context of the local gauge group $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$, we look for possible four family models, where all the particles carry ordinary electric charges. Thirteen different anomaly-free fermion structures emerge, out of which only two are realistic. For the simplest physical structure, we calculate the charged and neutral weak currents and the tree-level Fermion masses. We also look for new sources of flavor changing neutral currents in the quark sector, in connection with the upcoming experimental results at the Large Hadron Collider.Comment: Accepted for publication in Phys. Rev.

Flavor changing neutral currents with a fourth family of quarks

For a model with a fourth family of quarks, new sources of flavor changing neutral currents are identified by confronting the unitary 4x4 quark mixing matrix with the experimental measured values of the familiar 3x3 quark mixing matrix. By imposing as experimental constraints the known bounds for the flavor changing neutral currents, the largest mixing of the known quarks with the fourth family ones is established. The predictions are: a value for |V_{tb}| significantly different from unity, large rates for rare top decays as t->c\gamma and t->cZ, the last one reachable at the Large Hadrion Collider, and large rates for rare strange decays s->d\gamma and s->dg, where g stands for the gluon field.Comment: 7 pages, one figure. Published on Physical Review

Minimal ℤ' models for flavor anomalies

By allowing gauge anomaly cancellation between fermions in different families we find a non-universal solution for

Alternative 3-3-1 models: a comprehensive analysis

We systematically review how anomaly-free 3-3-1 models, with and without exotic electric charges, can be constructed using as a basis closed sets of fermions that include each of the particles and antiparticles of all electrically charged fields. Our analysis reproduces not only the models known in the literature, but also shows the existence of several more independent models for one and three families not considered so far. A phenomenological analysis of the new models is performed, in which the lower bounds at 95% CL on the gauge boson masses are presented

Systematic study of the SU(3) c ⊗ SU(3) L ⊗ U(1) x local gauge symmetry

We review in a systematic way how anomaly free SU(3) c ⊗ SU(3) L ⊗ U(1) x models without exotic electric charges can be constructed, using as basis closed sets of fermions which includes each one the particles and antiparticles of all the electrically charged fields. Our analysis reproduces not only the known models in the literature, but also shows the existence of several more independent models for one and three families not considered so far. A phenomenological analysis of the new models is done, where the lowest limits at a 95% CL on the gauge boson masses are presented