Amplitude analysis and branching fraction measurement of $D_s^{+}\to K^{-}{K}^{+}{\pi }^{+}{\pi }^{+}{\pi }^{-}$

Using $e^{+}{e}^{-}$ annihilation data corresponding to a total integrated luminosity of $6.32$ fb${}^{-1}$ collected at the center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform an amplitude analysis of the decay $D_s^{+}\to K^{-}{K}^{+}{\pi }^{+}{\pi }^{+}{\pi }^{-}$ and determine the relative fractions and phases of different intermediate processes. Absolute branching fraction of $D_s^{+}\to K^{-}{K}^{+}{\pi }^{+}{\pi }^{+}{\pi }^{-}$ decay is measured to be ($6.60\pm {0.47}_{\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.}}\pm {0.35}_{\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.}})\times {10}^{-3}$. The dominant intermediate process is $D_{s}^{+} \to a_1(1260)^+\phi, \phi\to K^-K^+, a_1(1260)^+\to \rho\pi^+, \rho\to\pi^+\pi^-$,withabranchingfractionof$(5.16\pm0.41_{\rm stat.}\pm0.27_{\rm syst.})\times 10^{-3}$.