Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
The fact that muon neutrinos nu(mu) oscillating into the mixture of tau neutrinos nu(tau) and sterile neutrinos nu(s) has been studied to explain the atmospheric nu(mu) disappearance. In this scenario, the effect of Earth matter is a key in determining the fraction of nu(s). Considering that the Earth matter density has uncertainty and this uncertainty has significant effects in some neutrino oscillation cases, such as the CP violation in very long baseline neutrino oscillations and the day-night asymmetry for solar neutrinos, we study the effects caused by this uncertainty in the above atmospheric nu(mu) oscillation scenario. We find that this uncertainty seems to have no significant effects and that the previous fitting results need not be modified.