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Register a new userScotogenic model for co-bimaximal mixing
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Pedro Miguel Martins Ferreira
Publication date
2016
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English
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We present a scotogenic model, i.e. a one-loop neutrino mass model with dark right-handed neutrino gauge singlets and one inert dark scalar gauge doublet $eta$, which has symmetries that lead to co-bimaximal mixing, i.e. to an atmospheric mixing angle $theta_{23} = 45^circ$ and to a $CP$-violating phase $delta = pm pi/2$, while the mixing angle $theta_{13}$ remains arbitrary. The symmetries consist of softly broken lepton numbers $L_alpha$ ($alpha = e,mu,tau$), a non-standard $CP$ symmetry, and three $Z_2$ symmetries. We indicate two possibilities for extending the model to the quark sector. Since the model has, besides $eta$, three scalar gauge doublets, we perform a thorough discussion of its scalar sector. We demonstrate that it can accommodate a Standard Model-like scalar with mass $125, mathrm{GeV}$, with all the other charged and neutral scalars having much higher masses.
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We consider an extension of the standard model with three Higgs doublet model and $S_3times mathbb{Z}_2$ discrete symmetries. Two of the scalar doublets are inert due to the $mathbb{Z}_2$ symmetry. We have calculated all the mass spectra in the scalar and lepton sectors and accommodated the leptonic mixing matrix as well. We also show that the model has scalar and pseudoscalar candidates to dark matter. Constraints on the parameters of the model coming from the decay $muto egamma$ were considered and we found signals between the current and the upcoming experimental limits, and from that decay we can predict the one-loop $muto eebar{e}$ channel.
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We construct a model for tri-bimaximal lepton mixing which employs only family symmetries and their soft breaking; neither vacuum alignment nor supersymmetry, extra dimensions, or non-renormalizable terms are used in our model. It is an extension of the Standard Model making use of the seesaw mechanism with five right-handed neutrino singlets. The scalar sector comprises four Higgs doublets and one complex gauge singlet. The horizontal symmetry of our model is based on the permutation group S_3 of the lepton families together with the three family lepton numbers--united this constitutes a symmetry group Delta(6infty^2). The model makes no predictions for the neutrino masses.
We present a flavor model of quarks and leptons with the non-Abelian discrete symmetry $S_4$ in the framework of the SU(5) SUSY GUT. Three generations of $bar 5$-plets in SU(5) are assigned to ${bf 3}$ of $S_4$ while the first and second generations of 10-plets in SU(5) are assigned to ${bf 2}$ of $S_4$, and the third generation of 10-plet is assigned to ${bf 1}$ of $S_4$. Right-handed neutrinos are also assigned to ${bf 2}$ for the first and second generations and ${bf 1}$ for the third generation. We predict the Cabibbo angle as well as the tri-bimaximal mixing of neutrino flavors. We also predict the non-vanishing $U_{e3}$ of the neutrino flavor mixing due to higher dimensional mass operators. Our predicted CKM mixing angles and the CP violation are consistent with experimental values. We also study SUSY breaking terms in the slepton sector. Our model leads to smaller values of flavor changing neutral currents than the present experimental bounds.
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