Statistical tests for zenith angle dependences of up-going μ-like neutrino events for multi-GeV region

Abstract

At the Neutrino 98 conference the Super Kamiokande collaboration presented a reduction of up-going μ-like events compared to down-going μ -like events by a factor of 0.54 −0.05 +0.06 for an exposure of 33 kton-years. Also, the zenith angle distribution observed by MACRO for -1 ≤ cos Θ ≤ −0.1 does not fit well for the no oscillation expectation. On the basis of x 2 tested results (shape, absolute value), however, their claim for neutrino oscillations cannot be considered to be firmly established from the standpoint of statistical evidence.