Analysis of the decay mode D0 → K−μ+ν

Fermilab high-energy photoproduction experiment E687 provides a high statistics sample of the decay mode D + → K ∗0 μ + ν (charge conjugates are implied). Our analysis yields a branching ratio of Γ (D + → K ∗0 μ + ν) Γ (D + → K − π + π + ) = 0.56±0.04±0.06 . The ratios of the form factors governing the decay are measured to be R ν = 1.74 ±0.27±0.28 and R 2 = 0.78±0.18±0.10, implying a polarization of Γ l Γ t = 1.20±0.13 ±0.13 for the electron decay. Finally, we report new limits on the decay modes D + → K − π + μ + ν (nonresonent) and D + → K ∗0 π 0 μ + ν .