부산대학교 도서관

We present an extension $U(1)_{X}$ to the Standard Model that reproduces the lepton mass structures determined by the experiments. In the charged sector, we introduced effective operators of dimension $n = 7$ to generate the mass of the electron, which is null at tree-level due to the $X$ charge. In the neutral sector, we added three sterile right-handed neutrinos and three Majorana neutrinos to generate the mass structure for the left-handed neutrinos, by the inverse seesaw mechanism. The model free parameters were fitted with the known mass eigenvalues $m_{e},\,m_{\mu},\,m_{\tau}$, and with the most recent results of a global analysis of the data from neutrino oscillation. From the adjustment of the free parameters, we obtained allowed regions for the Yukawa coupling set.