Active to sterile neutrino oscillations: Coherence and MINOS results

Understand

We study the $\nu_\mu - \nu_s$ oscillation effects in the near detector of the MINOS experiment.

• Conceptually, the MINOS search for sterile neutrinos with mass $\sim 1$ eV realizes an interesting situation of partial decoherence of the neutrino state at the production.
• This corresponds to a difference of energies of the two mass eigenstates that is comparable with or bigger than the width of the initial state (pion).
• We show that these effects modify the MINOS bound on mixing of sterile neutrino for $\Delta m^2_{41} \aprge 0.5$ eV$^2$ and make the experiment insensitive to oscillations with $\Delta m^2_{41} \gtrsim 15$ eV$^2$.