Measurement of the branching ratio of the decay D0→π−μ+ν relative to D0→K−μ+ν

We present a new measurement of the branching ratio of the Cabibbo suppressed decay D0→π−μ+ν relative to the Cabibbo favored decay D0→K−μ+ν and an improved measurement of the ratio |f+π(0)/f+K(0)|. Our results are 0.074±0.008±0.007 for the branching ratio and 0.85±0.04±0.04±0.01 for the form factor ratio, respectively.