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

Abstract

We measure the mass difference between $D_s^{\ast +}$ and $D_s^{+}$, $\hat{I}”m_s$, using the decay chain $D_s^{\ast +}\to D_s^{+}(\to K^{+}{K}^{-}\ddot{I}{€}^{+})\ddot{I}{€}^0$, utilizing $e^{+}{e}^{-}$ annihilation data corresponding to an integrated luminosity of 3.19 fb${}^{-1}$ collected at a center-of-mass energy of 4.178 GeV with the BESIII detector. The measured value of $\hat{I}”m_s=[144201.9\pm 44.2(stat.)\pm 29.9(syst.)\pm 15.0(\mathrm{PDG})]$ keV/$c^2$ is about seven times more precise than the current Particle Data Group average, where the last uncertainty is from the Particle Data Group average of the $D^{\ast +}-D^{+}$ mass difference.