Experimental comparison of neutrino and muon velocities

The velocities of neutrinos and muons originating from π+ and K+ decays have been compared using the California Institute of Technology-Fermilab detector in a narrow-band neutrino beam. A time-of-flight comparison between positive muons and neutrinos, as indicated by the final-state negative muons in neutrino interactions, yields absolute value(β/sub v/-β/sub μ) < or = 0.4 x 10-3 (99% confidence level). We assume that absolute value (1-β/sub μ/) <10-5 for these muons