Search for Differences in Oscillation Parameters for Atmospheric Neutrinos and Antineutrinos at Super-Kamiokande

We present a search for differences in the oscillations of antineutrinos and neutrinos in the Super-Kamiokande-I, -II, and -III atmospheric neutrino sample. Under a two-flavor disappearance model with separate mixing parameters between neutrinos and antineutrinos, we find no evidence for a difference in oscillation parameters. Best-fit antineutrino mixing is found to be at ({Delta}m{sup 2},sin{sup 2}2{theta})= (2.0x10{sup -3} eV{sup 2},1.0) and is consistent with the overall Super-K measurement.