2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/48950The dispersion relation of energetic (few TeV) neutrinos traversing a medium is studied. We use the real time formalism of thermal field theory and we include the effects from the propagator of the W gauge boson. We consider then the MSW oscillations for cosmic neutrinos traversing the Earth, adopting for the neutrino parameters values suggested by the LSND results. It is found that the $ν_μ$ flux, for neutrinos passing through the center of the Earth, will appear reduced by 15% for energies around 10 TeV.12 pages, latex, 2 figuresHigh Energy Physics - PhenomenologyAstrophysicstext