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Register a new userCP Phases of Neutrino Mixing in a Supersymmetric B-L Gauge Model with T_7 Lepton Flavor Symmetry
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In a recently proposed renormalizable model of neutrino mixing using the non-Abelian discrete symmetry T_7 in the context of a supersymmetric extension of the Standard Model with gauged U(1)_{B-L}, a correlation was obtained between theta_{13} and theta_{23} in the case where all parameters are real. Here we consider all parameters to be complex, thus allowing for one Dirac CP phase delta_{CP} and two Majorana CP phases alpha_{1,2}. We find a slight modification to this correlation as a function of delta_{CP}. For a given set of input values of Delta m^2_{21}, Delta m^2_{32}, theta_{12}, and theta_{13}, we obtain sin^2 2 theta_{23} and m_{ee} (the effective Majorana neutrino mass in neutrinoless double beta decay) as functions of tan delta_{CP}. We find that the structure of this model always yields small |tan delta_{CP}|.
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We study a neutrino mass model based on $S_4$ flavor symmetry which accommodates lepton mass, mixing with non-zero $theta_{13}$ and CP violation phase. The spontaneous symmetry breaking in the model is imposed to obtain the realistic neutrino mass and mixing pattern at the tree- level with renormalizable interactions. Indeed, the neutrinos get small masses from one $SU(2)_L$ doubplet and two $SU(2)_L$ singlets in which one being in $underline{2}$ and the two others in $underline{3}$ under $S_4$ with both the breakings $S_{4}rightarrow S_3$ and $S_{4}rightarrow Z_3$ are taken place in charged lepton sector and $S_4rightarrow mathcal{K}$ in neutrino sector. The model also gives a remarkable prediction of Dirac CP violation $delta_{CP}=frac{pi}{2}$ or $-frac{pi}{2}$ in the both normal and inverted spectrum which is still missing in the neutrino mixing matrix. The relation between lepton mixing angles is also represented.
The latest measurements of the anomalous muon magnetic moment $a^{}_mu equiv (g^{}_mu - 2)/2$ show a $4.2sigma$ discrepancy between the theoretical prediction of the Standard Model and the experimental observations. In order to account for such a discrepancy, we consider a possible extension of the type-(I+II) seesaw model for neutrino mass generation with a gauged $L^{}_mu - L^{}_tau$ symmetry. By explicitly constructing an economical model with only one extra scalar singlet, we demonstrate that the gauge symmetry $U(1)^{}_{L^{}_mu - L^{}_tau}$ and its spontaneous breaking are crucially important not only for explaining the muon $(g - 2)$ result but also for generating neutrino masses and leptonic flavor mixing. Various phenomenological implications and experimental constraints on the model parameters are also discussed.
A multiscalar and nonrenormalizable $B-L$ extension of the standard model (SM) with $S_4$ symmetry which successfully explains the recent observed neutrino oscillation data is proposed. The tiny neutrino masses and their hierarchies are generated via the type-I seesaw mechanism. The model reproduces the recent experiments of neutrino mixing angles and Dirac CP violating phase in which the atmospheric angle $(theta_{23})$ and the reactor angle $(theta_{13})$ get the best-fit values while the solar angle $(theta_{12})$ and Dirac CP violating phase ($delta $) belong to $3, si $ range of the best-fit value for normal hierarchy (NH). For inverted hierarchy (IH), $theta_{13}$ gets the best-fit value and $theta_{23}$ together with $de $ belongs to $1, si $ range while $theta_{12}$ belongs to $3, si $ range of the best-fit value. The effective neutrino masses are predicted to be $langle m_{ee}rangle=6.81 ,, mbox{meV}$ for NH and $langle m_{ee}rangle=48.48,, mbox{meV}$ for IH being in good agreement with the most recent experimental data.
We construct a multiscalar and nonrenormalizable $B-L$ model with $A_4times Z_3times Z_4$ flavor symmetry which successfully explains the recent $3+1$ active-sterile neutrino data. The tiny neutrino mass the mass hierarchy are obtained by the type-I seesaw mechanism. The hierarchy of the lepton masses is satisfied by a factor of $v_H left(frac{v_l}{Lambda}right)^2 sim 10^{-4}, mathrm{GeV}$ of the electron mass compared to the muon and tau masses of the order of $frac{v_H v_l}{Lambda} sim 10^{-1}, mathrm{GeV}$. The recent $3+1$ active-sterile neutrino mixings are predicted to be $0.015 leq|U_{e 4}|^2leq 0.045$, $0.004 leq|U_{mu 4}|^2leq 0.012$, $0.004 leq|U_{tau 4}|^2leq 0.014$ for normal hierarchy and $0.020leq|U_{e 4}|^2leq 0.045$, $0.008 leq|U_{mu 4}|^2leq 0.018$, $0.008leq|U_{tau 4}|^2leq 0.022$ for inverted hierarchy. Sterile neutrino masses are predicted to be $0.7 lesssim m_s , (mathrm{eV}) lesssim 3.16$ for normal hierarchy and $2.6 lesssim m_s , (mathrm{eV}) lesssim 7.1$ for inverted hierarchy. For three neutrino scheme the model predicts $0.3401 leq sin^2theta_{12}leq 0.3415, , 0.460 leq sin^2theta_{23}leq 0.540,, -0.60 leq sindelta_{CP}leq -0.20$ for normal hierarchy and $0.3402 leq sin^2theta_{12}leq 0.3416,, 0.434leqsin^2theta_{23}leq 0.610,, -0.95 leq sindelta_{CP}leq -0.60$ for inverted hierarchy. The effective neutrino masses are predicted to be $35.70 leq langle m_{ee}rangle [mbox{meV}] leq 36.50$ in 3+1 scheme and $3.65 leq langle m^{(3)}_{ee}rangle [mbox{meV}] leq 4.10$ in three neutrino scheme for NH while $160.0 leq langle m_{ee}rangle [mbox{meV}] leq 168.0$ in 3+1 scheme and $47.80 leq langle m^{(3)}_{ee}rangle [mbox{meV}] leq 48.70$ in three neutrino scheme for for IH which are all in agreement with the recent experimental data.
We discuss a classically conformal radiative neutrino model with gauged B$-$L symmetry, in which the B$-$L symmetry breaking can occur through the Coleman-Weinberg mechanism. As a result, Majorana mass term is generated and EW symmetry breaking also occurs. We show some allowed parameters to satisfy several theoretical and experimental constraints. Theoretical constraints are inert conditions and Coleman-Weinberg condition. Experimental bounds are lepton flavor violation(especially mu -> e gamma), the current bound on the $Z$ mass at LHC, in additions to the neutrino oscillations.
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