Improved measurement of the absolute branching fraction of D⁺→ K̄⁰ μ ⁺ν μ D + → K ¯ 0 μ + ν μ

By analyzing 2.93 fb ⁻¹ of data collected at √s=3.773 GeV with the BESIII detector, we measure the absolute branching fraction B(D⁺→ K̄⁰μ ⁺ν μ)=(8.72 ± 0.07ₛtat. ± 0.18ₛys.)% , which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of B(D⁰→ K⁻μ ⁺ν _μ ) , B(D⁺→ K̄⁰ e⁺ν ₑ) , and the lifetimes of the D⁰ and D⁺ mesons with the value of B(D⁺→ K̄⁰ μ ⁺ν μ) measured in this work, we determine the following ratios of partial widths: Γ (D⁰→ K⁻μ ⁺ν _μ )/Γ (D⁺→ K̄⁰μ ⁺ν μ)=0.963± 0.044 and Γ (D⁺→ K̄⁰ μ ⁺ν μ)/Γ (D⁺→ K̄⁰ e⁺ν ₑ)=0.988± 0.033 .