Amplitude analysis and branching fraction measurement of Ds+ → K ⁻ K ⁺ π ⁺ π ⁺ π ⁻

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 Ds+ → K⁻K⁺π⁺π⁺π⁻ and determine the relative fractions and phases of different intermediate processes. Absolute branching fraction of Ds+→ K⁻K⁺π⁺π⁺π⁻ decay is measured to be (6.60 ± 0.47_stat.± 0.38_syst.) × 10⁻³. The dominant intermediate process is Ds+→ a₁(1260)⁺ϕ, ϕ → K⁻K⁺, a₁(1260)⁺→ ρπ⁺, ρ → π⁺π⁻, with a branching fraction of (5.15 ± 0.41_stat.± 0.32_syst.) × 10⁻³. [Figure not available: see fulltext.]