Four-neutrino model and the K2K experiment

Abstract

We investigate the neutrino oscillations of ν_μbeam at the K2K experiment in the four-neutrino model with three active and one sterile neutrinos, and compare them with the oscillations in the three-neutrino model. In the four-neutrino case, the effect of the Δm^2_{LSND} scale of mass-squared difference, derived from the LSND experiments, occurs in the survival probability P(ν_μ\to ν_μ) in the range of Δm^2 < 0.004 eV^2, where Δm^2 is the relevant one to the K2K experiment and corresponds to the atmospheric neutrino mass scale. Once the probability P(ν_μ\to ν_μ) is measured at the K2K, the allowed region of Δm^2 would turn out to be broader in the four-neutrino model than the one in the three-neutrino model.