Search for U(1)Lμ-Lτ charged dark matter with neutrino telescope

We study a simple Dirac fermion dark matter model in U(1)(L mu-L tau) theory. The new light gauge boson X plays important roles in both dark matter physics and the explanation for the muon g-2 anomaly. The observed dark matter relic density is realized by a large U(1)(L mu-L tau) charge without introducing a resonance effect of the X boson. As a by-product of the model, characteristic neutrino signatures from sub-GeV dark matter psi are predicted depending on the mass spectrum. We formulate the analysis of psi(psi) over bar -> nu(nu) over bar, and of psi(psi) over bar -> XX followed by X -> nu(nu) over bar in a model independent way. The energy spectrum of neutrinos in the former process is monochromatic while in the latter process is bowl-shape. We also evaluate sensitivity at Super-Kamiokande and future Hyper-Kamiokande detectors. The analysis is finally applied to the U(1)(L mu-L tau) dark matter model.