Amplitude analysis and branching-fraction measurement of D s + → K S 0 π + π 0 $$ {D}_s^{+}\to {K}_S^0{\pi}^{+}{\pi}^0 $$

Abstract By using 6.32 fb −1 of data collected with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, we perform an amplitude analysis of the decay D s + → K S 0 π + π 0 $$ {D}_s^{+}\to {K}_S^0{\pi}^{+}{\pi}^0 $$ and determine the relative fractions and phase differences of different intermediate processes, which include K S 0 ρ $$ {K}_S^0\rho $$ (770)+, K S 0 ρ $$ {K}_S^0\rho $$ (1450)+, K *(892)0 π +, K *(892)+ π 0, and K *(1410)0 π +. With the detection efficiency based on the amplitude analysis results, the absolute branching fraction is measured to be ℬ D s + → K S 0 π + π 0 = 5.43 ± 0.30 stat ± 0.15 syst × 10 − 3 $$ \mathrm{\mathcal{B}}\left({D}_s^{+}\to {K}_S^0{\pi}^{+}\pi 0\right)=\left(5.43\pm {0.30}_{\mathrm{stat}}\pm {0.15}_{\mathrm{syst}}\right)\times {10}^{-3} $$ .