Neutrino Masses, Leptonic Flavor Mixing and Muon $(g-2)$ in the Seesaw Model with the $U(1{)}_{L_{\mu }^{}-L_{\tau }^{}}^{}$ Gauge Symmetry

Abstract

The latest measurements of the anomalous muon magnetic moment $a_{\mu }^{}\equiv (g_{\mu }^{}-2)/2$ show a $4.2\sigma$ 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.

Comments: 23 pages, 3 figures, 1 table, typos corrected, more references added, to appear in Chin. Phys. C