Estimating Δ${\mathrm{\Gamma }}_{\mathit{D}}$ and the long-distance contribution to Δ${\mathit{m}}_{\mathit{D}}$

Based on the potential model, we estimate the long-distance contributions from one-meson intermediate states to Δ${\mathit{m}}_{\mathit{D}}$ and have found that it is 5–6 times larger than that from two-meson intermediate states. ΔΓ=${\mathrm{\Gamma }}_{\mathit{D}\mathit{S}}$-${\mathrm{\Gamma }}_{\mathit{D}\mathit{L}}$ is also calculated and not only are the ordinary meson states considered, but the diquark states which convert to ordinary mesons through strong interaction are also taken into account. The numerical result is ΔΓ/Γ≃3–4%: too small to be observed in the near future.