Precise Measurement of the $e^{+}{e}^{-}\to D_s^{*+}{D}_s^{*-}$ Cross Sections at Center-of-Mass Energies from Threshold to 4.95 GeV

The process $e^{+}{e}^{-}\to D_s^{*+}{D}_s^{*-}$ is studied with a semi-inclusive method using data samples at center-of-mass energies from threshold to 4.95 GeV collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross sections of the process are measured for the first time with high precision in this energy region. Two resonance structures are observed in the energy-dependent cross sections around 4.2 and 4.4 GeV. By fitting the cross sections with a coherent sum of three Breit-Wigner amplitudes and one phase-space amplitude, the two significant structures are assigned masses of $(4186.8\pm 8.7\pm 30)$ and $(4414.6\pm 3.4\pm 6.1)\mathrm{MeV}/c^2$, widths of $(55\pm 15\pm 53)$ and $(122.5\pm 7.5\pm 8.1)\mathrm{MeV}$, where the first errors are statistical and the second ones are systematic. The inclusion of a third Breit-Wigner amplitude is necessary to describe a structure around 4.79 GeV.

Figure 1

The $M_{\gamma KK\pi }$ distribution for data at 4.29 GeV. The black curve represents the fit, the red dashed curve the background, the blue dot-dashed curve the random combinations of $\gamma KK\pi$ from $e^{+}{e}^{-}\to D_s^{*\pm }{D}_s^{*\mp }$, and the blue dashed curve the correct $\gamma KK\pi$ combinations from the signal.

Figure 2

Three fitting results for the measured dressed cross sections of $e^{+}{e}^{-}\to D_s^{*+}{D}_s^{*-}$. The black dots with error bars are for the measured dressed cross sections. In each plot, the black curve represents the fit; the green dashed, blue two-dashed, and red long-dashed ones are for the three BW amplitudes from the fit, respectively, and the pink dot-dashed is for the PHSP contributions.