Measurement of the branching ratio of the decay D^0 -> π^-μ^+νrelative to D^0 -> K^-μ^+ν

Abstract

We present a new measurement of the branching ratio of the Cabibbo suppressed decay D^0\to π^-μ^+νrelative to the Cabibbo favored decay D^0\to K^-μ^+νand an improved measurement of the ratio |\frac{f_+^π(0)}{f_+^{K}(0)}|. Our results are 0.074 \pm 0.008 \pm 0.007 for the branching ratio and 0.85 \pm 0.04 \pm 0.04 \pm 0.01 for the form factor ratio, respectively.