Non-adiabatic Level Crossing in Resonant Neutrino Oscillations

Analytic results are presented for the probability of detecting an electron neutrino after passage through a resonant oscillation region. If the electron neutrino is produced far above the resonance density, this probability is simply given by $\langle \,P_{\nu_e} \, \rangle \approx \sin^2 \theta_0+ P_\text{x} \cos 2 \theta_0$, where $\theta_0$ is the vacuum mixing angle. The probability is averaged over the production as well as the detection positions of the neutrino and $P_\text{x}$ is the Landau-Zener transition probability between adiabatic states. Finally, this result is applied to resonance oscillations within the solar interior.