Precision Measurement of the $D_s^{\ast +}-D_s^{+}$ Mass Difference

Abstract

We have measured the vector-pseudoscalar mass splitting $M(D_s^{\ast +})-M(D_s^{+})=144.22\pm 0.47\pm 0.37MeV$, significantly more precise than the previous world average. We minimize the systematic errors by also measuring the vector-pseudoscalar mass difference $M(D^{\ast 0})-M(D^0)$ using the radiative decay $D^{\ast 0}\to D^0\gamma$, obtaining $[M(D_s^{\ast +})-M(D_s^{+})]-[M(D^{\ast 0})-M(D^0)]=2.09\pm 0.47\pm 0.37MeV$. This is then combined with our previous high-precision measurement of $M(D^{\ast 0})-M(D^0)$, which used the decay $D^{\ast 0}\to D^0{\pi }^0$. We also measure the mass difference $M(D_s^{+})-M(D^{+})=99.5\pm 0.6\pm 0.3$ MeV, using the $\varphi {\pi }^{+}$ decay modes of the $D_s^{+}$ and $D^{+}$ mesons.

Comments: 18 pages uuencoded compressed postscript (process with uudecode then gunzip). hardcopies with figures can be obtained by sending mail to: preprints@lns62.lns.cornell.edu