  The OPERA Collaboration reported evidence for muonic neutrinos traveling
slightly faster than light in vacuum. While waiting further checks from the
experimental community, here we aim at exploring some theoretical consequences
of the hypothesis that muonic neutrinos are superluminal, considering in
particular the tachyonic and the Coleman-Glashow cases. We show that a
tachyonic interpretation is not only hardly reconciled with OPERA data on
energy dependence, but that it clashes with neutrino production from pion and
with neutrino oscillations. A Coleman-Glashow superluminal neutrino beam would
also have problems with pion decay kinematics for the OPERA setup; it could be
easily reconciled with SN1987a data, but then it would be very problematic to
account for neutrino oscillations.
