Observation of a Resonant Structure in ${e}^{+}{e}^{-}\to {K}^{+}{K}^{-}{\pi }^{0}{\pi }^{0}$

A partial-wave analysis is performed for the process ${e}^{+}{e}^{-}\to {K}^{+}{K}^{-}{\pi }^{0}{\pi }^{0}$ at the center-of-mass energies ranging from 2.000 to 2.644 GeV. The data samples of ${e}^{+}{e}^{-}$ collisions, collected by the BESIII detector at the BEPCII collider with a total integrated luminosity of $300\text{}\text{}{\mathrm{pb}}^{-1}$, are analyzed. The total Born cross sections for the process ${e}^{+}{e}^{-}\to {K}^{+}{K}^{-}{\pi }^{0}{\pi }^{0}$, as well as the Born cross sections for the subprocesses ${e}^{+}{e}^{-}\to \varphi {\pi }^{0}{\pi }^{0}$, ${K}^{+}\left(1460\right){K}^{-}$, ${K}_{1}^{+}\left(1400\right){K}^{-}$, ${K}_{1}^{+}\left(1270\right){K}^{-}$, and ${K}^{*+}\left(892\right){K}^{*-}\left(892\right)$, are measured versus the center-of-mass energy. The corresponding results for ${e}^{+}{e}^{-}\to {K}^{+}{K}^{-}{\pi }^{0}{\pi }^{0}$ and $\varphi {\pi }^{0}{\pi }^{0}$ are consistent with those of BABAR with better precision. By analyzing the cross sections for the four subprocesses, ${K}^{+}\left(1460\right){K}^{-}$, ${K}_{1}^{+}\left(1400\right){K}^{-}$, ${K}_{1}^{+}\left(1270\right){K}^{-}$, and ${K}^{*+}\left(892\right){K}^{*-}\left(892\right)$, a structure with mass $M=\left(2126.5±16.8±12.4\right)\text{}\text{}\mathrm{MeV}/{c}^{2}$ and width $\Gamma =\left(106.9±32.1±28.1\right)\text{}\text{}\mathrm{MeV}$ is observed with an overall statistical significance of $6.3\sigma $, although with very limited significance in the subprocesses ${e}^{+}{e}^{-}\to {K}_{1}^{+}\left(1270\right){K}^{-}$ and ${K}^{*+}\left(892\right){K}^{*-}\left(892\right)$. The resonant parameters of the observed structure suggest it can be identified with the $\varphi \left(2170\right)$, thus the results provide valuable input to the internal nature of the $\varphi \left(2170\right)$.