Study of the decay $D_s^{+}\to K_S^0{K}_S^0\ddot{I}{€}^{+}$ and observation an isovector partner to $f_0(1710)$

Abstract

Using $e^{+}{e}^{-}$ annihilation data corresponding to a total integrated luminosity of 6.32 $\mathrm{f}{\mathrm{b}}^{-1}$ collected at center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform an amplitude analysis of the decay $D_s^{+}\to K_S^0{K}_S^0\ddot{I}{€}^{+}$ for the first time. An enhancement is observed in the $K_S^0{K}_S^0$ mass spectrum near 1.7 GeV/$c^2$, which was not seen in $D_s^{+}\to K^{+}{K}^{-}\ddot{I}{€}^{+}$ in an earlier work, implying the existence of an isospin one partner of the $f_0(1710)$. The branching fraction of the decay $D_s^{+}\to K_S^0{K}_S^0\ddot{I}{€}^{+}$ is determined to be $\mathcal{B}(D_s^{+}\to K_S^0{K}_S^0\ddot{I}{€}^{+})=(0.68\pm 0.04_{\mathrm{stat}}\pm 0.01_{\mathrm{syst}})\%$.

8 pages, 3 figures