Sterile Neutrino Fits
  After a brief review of the results of solar, atmospheric and long-baseline
neutrino oscillation experiments which led to the current three-neutrino mixing
paradigm, we discuss indications of neutrino oscillation experiments in favor
of short-baseline oscillations which require the existence of one or more
sterile neutrinos. We show that the simplest possibility of existence of one
sterile neutrino is not enough to fit all data of short-baseline neutrino
oscillation experiments because of two tensions: a tension between neutrino and
antineutrino data and a tension between appearance and disappearance data. The
tension between neutrino and antineutrino data is eliminated with the addition
of a second sterile neutrino which allows CP-violating effects in
short-baseline experiments. In this case the tension between appearance and
disappearance data is reduced, but cannot be eliminated.
