We have measured the vector-pseudoscalar mass splitting M(Ds∗+​)−M(Ds+​)=144.22±0.47±0.37MeV, significantly more precise than the previous
world average. We minimize the systematic errors by also measuring the
vector-pseudoscalar mass difference M(D∗0)−M(D0) using the radiative
decay D∗0→D0γ, obtaining
[M(Ds∗+​)−M(Ds+​)]−[M(D∗0)−M(D0)]=2.09±0.47±0.37MeV. This is
then combined with our previous high-precision measurement of
M(D∗0)−M(D0), which used the decay D∗0→D0π0. We also
measure the mass difference M(Ds+​)−M(D+)=99.5±0.6±0.3 MeV, using the
ϕπ+ decay modes of the Ds+​ and D+ mesons.Comment: 18 pages uuencoded compressed postscript (process with uudecode then
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