In this talk I discuss some scenarios where new states affect the standard neutrino oscillation probability. I first discuss light sterile neutrinos with a particular focus on the current status of the reactor antineutrino anomaly. Next I discuss theoretically motivated models. First I show how large extra dimensions can induce new oscillations lengths and show the bounds which can be obtained from current and future neutrino experiments. Finally I discuss how the presence of heavy sterile neutrinos affects the unitarity of the lepton mixing matrix and show updated bounds on the deviation from unitarity using neutrino oscillation data.
AHEP