CONSTRAINTS ON 3-NEUTRINO MIXING FROM ATMOSPHERIC AND REACTOR DATA

Observations of atmospheric neutrinos are usually analyzed using the s imPlifYing approximation that either nu(mu) <-- --> nu(tau) or nu(e) < -- --> nu(mu) two-flavor mixing is relevant. Here we instead consider the data using the simplifying approximation that only one neutrino ma ss scale is relevant. This approximation is the minimal three-flavor n otation that includes the two relevant two-flavor approximations. The constraints in the parameter space orthogonal to the usual, two-flavor analyses are studied.