  Characteristic patterns of cosmic neutrino spectrum reported by the IceCube
collaboration and long-standing inconsistency between theory and experiment in
muon anomalous magnetic moment are simultaneously explained by an extra
leptonic force mediated by a gauge field with a mass of the MeV scale. With
different assumptions for redshift distribution of cosmic neutrino sources,
diffuse neutrino flux is calculated with the scattering between cosmic neutrino
and cosmic neutrino background through the new leptonic force. Our analysis
sheds light on a relation among lepton physics at the three different scales,
PeV, MeV, and eV, and provides possible clues to the distribution of sources of
cosmic neutrino and also to neutrino mass spectrum.
