Amplitude analysis of D⁰ →k^-π⁺π⁺π^-

We present an amplitude analysis of the decay D0→K-π+π+π- based on a data sample of 2.93 fb-1 acquired by the BESIII detector at the ψ(3770) resonance. With a nearly background free sample of about 16000 events, we investigate the substructure of the decay and determine the relative fractions and the phases among the different intermediate processes. Our amplitude model includes the two-body decays D0→K̄∗0ρ0, D0→K-a1+(1260) and D0→K1-(1270)π+, the three-body decays D0→K̄∗0π+π- and D0→K-π+ρ0, as well as the four-body nonresonant decay D0→K-π+π+π-. The dominant intermediate process is D0→K-a1+(1260), accounting for a fit fraction of 54.6%.