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Register a new userMuon $g-2$ in $U(1)_{mu-tau}$ Symmetric Gauged Radiative Neutrino Mass Model
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We explore muon anomalous magnetic moment (muon $g-2$) in a scotogenic neutrino model with a gauged lepton numbers symmetry $U(1)_{mu-tau}$. In this model, a dominant muon $g-2$ contribution comes from not an additional gauge sector but the Yukawa sector. In our numerical $Delta chi^2$ analysis, we show that our model is in favor of normal hierarchy with some features. We also demonstrate two benchmark points, satisfying muon $g-2$ at the best fit value $25.1times10^{-10}$.
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The tightening of the constraints on the standard thermal WIMP scenario has forced physicists to propose alternative dark matter (DM) models. One of the most popular alternate explanations of the origin of DM is the non-thermal production of DM via freeze-in. In this scenario the DM never attains thermal equilibrium with the thermal soup because of its feeble coupling strength ($sim 10^{-12}$) with the other particles in the thermal bath and is generally called the Feebly Interacting Massive Particle (FIMP). In this work, we present a gauged U(1)$_{L_{mu}-L_{tau}}$ extension of the Standard Model (SM) which has a scalar FIMP DM candidate and can consistently explain the DM relic density bound. In addition, the spontaneous breaking of the U(1)$_{L_{mu}-L_{tau}}$ gauge symmetry gives an extra massive neutral gauge boson $Z_{mutau}$ which can explain the muon ($g-2$) data through its additional one-loop contribution to the process. Lastly, presence of three right-handed neutrinos enable the model to successfully explain the small neutrino masses via the Type-I seesaw mechanism. The presence of the spontaneously broken U(1)$_{L_{mu}-L_{tau}}$ gives a particular structure to the light neutrino mass matrix which can explain the peculiar mixing pattern of the light neutrinos.
Gauged $U(1)_{L_mu - L_tau}$ model has been advocated for a long time in light of muon $g-2$ anomaly, which is a more than $3sigma$ discrepancy between the experimental measurement and the standard model prediction. We augment this model with three right-handed neutrinos $(N_e, N_mu, N_tau)$ and a vector-like singlet fermion $(chi)$ to explain simultaneously the non-zero neutrino mass and dark matter content of the Universe, while satisfying anomalous muon $g-2$ constraints. It is shown that in a large parameter space of this model we can explain positron excess, observed at PAMELA, Fermi-LAT and AMS-02, through dark matter annihilation, while satisfying the relic density and direct detection constraints.
We present an economical model where an $S^{}_1$ leptoquark and an anomaly-free $U(1)^{}_X$ gauge symmetry with $X = B^{}_3-2L^{}_mu/3-L^{}_tau/3$ are introduced, to account for the muon anomalous magnetic moment $a^{}_mu equiv (g^{}_mu-2)$ and flavor puzzles including $R^{}_{K^{(ast)_{}}}$ and $R^{}_{D^{(ast)_{}}}$ anomalies together with quark and lepton flavor mixing. The $Z^prime_{}$ gauge boson associated with the $U(1)^{}_X$ symmetry is responsible for the $R^{}_{K^{(ast)_{}}}$ anomaly. Meanwhile, the specific flavor mixing patterns of quarks and leptons can be generated after the spontaneous breakdown of the $U(1)^{}_X$ gauge symmetry via the Froggatt-Nielsen mechanism. The $S^{}_1$ leptoquark which is also charged under the $U(1)^{}_X$ gauge symmetry can simultaneously explain the latest muon $(g-2)$ result and the $R^{}_{D^{(ast)_{}}}$ anomaly. In addition, we also discuss several other experimental constraints on our model.
We propose an extension of the Standard Model (SM) for radiative neutrino mass by introducing a dark $U(1)_D$ gauge symmetry. The kinetic mixing between the SM gauges and the dark $U(1)_D$ gauge arises at 1-loop mediated by new inert scalar fields. We show that the tiny neutrino mass and dark matter candidates are naturally accommodated. Motivated by the recent measurement of $(g-2)_{mu}$ indicating $4.2~ sigma$ deviation from the SM prediction, we examine how the deviation $Delta a_{mu}$ can be explained in this model.
The observation of neutrino masses, mixing and the existence of dark matter are amongst the most important signatures of physics beyond the Standard Model (SM). In this paper, we propose to extend the SM by a local $L_mu - L_tau$ gauge symmetry, two additional complex scalars and three right-handed neutrinos. The $L_mu - L_tau$ gauge symmetry is broken spontaneously when one of the scalars acquires a vacuum expectation value. The $L_mu - L_tau$ gauge symmetry is known to be anomaly free and can explain the beyond SM measurement of the anomalous muon $({rm g-2})$ through additional contribution arising from the extra $Z_{mutau}$ mediated diagram. Small neutrino masses are explained naturally through the Type-I seesaw mechanism, while the mixing angles are predicted to be in their observed ranges due to the broken $L_mu-L_tau$ symmetry. The second complex scalar is shown to be stable and becomes the dark matter candidate in our model. We show that while the $Z_{mutau}$ portal is ineffective for the parameters needed to explain the anomalous muon $({rm g-2})$ data, the correct dark matter relic abundance can easily be obtained from annihilation through the Higgs portal. Annihilation of the scalar dark matter in our model can also explain the Galactic Centre gamma ray excess observed by Fermi-LAT. We show the predictions of our model for future direct detection experiments and neutrino oscillation experiments.
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