Amplitude analysis and branching fraction measurement of D_s^+ → 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 D_s^+ → K − K + π + π + π − and determine the relative fractions and phases of different intermediate processes. Absolute branching fraction of D_s^+ → 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 D_s^+ → a 1 (1260) + ϕ, ϕ → K − K + , a 1 (1260) + → ρπ + , ρ → π + π − , with a branching fraction of (5 . 15 ± 0 . 41 stat . ± 0 . 32 syst . ) × 10 − 3 .