Gauged $U(1{)}_{L_{\hat{I}}¼-L_{\ddot{I}}„}$ Scotogenic Model in light of $R_{K^{(\ast )}}$ Anomaly and AMS-02 Positron Excess

Abstract

We study the gauged $U(1{)}_{L_{\hat{I}}¼-L_{\ddot{I}}„}$ scotogenic model with emphasis on latest measurement of LHCb $R_{K^{(\ast )}}$ anomaly and AMS-02 positron excess. In this model, neutrino masses are induced at one-loop level with $Z_2$-odd particles, i.e., right-handed neutrinos $N_{\ell }(\ell =e,\hat{I}¼,\ddot{I}„)$ and inert scalar doublet $\hat{I}\cdot$ inside the loop. Meanwhile, the gauged $U(1{)}_{L_{\hat{I}}¼-L_{\ddot{I}}„}$ symmetry is broken spontaneously by the scalar singlet $S$, resulting to the massive gauge boson $Z^{\prime }$. Provided certain couplings to quarks induced by heavy vector-like quarks, the gauge boson $Z^{\prime }$ would contribute to the transition $b\to s\hat{I}{¼}^{+}\hat{I}{¼}^{-}$, hence explain the $R_{K^{(\ast )}}$ anomaly. As for the Majorana fermion DM $N$, the gauge boson $Z^{\prime }$ and the singlet Higgs $H_0$ will generate various annihilation channels, among which the $NN\to Z^{\prime }{Z}^{\prime }$ and $NN\to Z^{\prime }{H}_0(\to Z^{\prime }{Z}^{\prime })$ channel could be used to interpret the AMS-02 positron excess. We give a comprehensive analysis on model parameter space with consider various current constraints. The combined analysis shows that the $R_{K^{(\ast )}}$ anomaly and AMS-02 positron excess can be explained simultaneously.