Amplitude analysis of the Ds+​→ π−π+π+ decay

A Dalitz plot analysis of the Ds+​ → π−π+π+ decay is presented. The analysis is based on proton-proton collision data recorded by the LHCb experiment at a centre-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 1.5 fb−1. The resonant structure of the decay is obtained using a quasi-model-independent partial-wave analysis, in which the π+π− S-wave amplitude is parameterised as a generic complex function determined by a fit to the data. The S-wave component is found to be dominant, followed by the contribution from spin-2 resonances and a small contribution from spin-1 resonances. The latter includes the first observation of the Ds+​→ ω(782)π+ channel in the Ds+​→ π−π+π+ decay. The resonant structures of the Ds+​→ π−π+π+ and D+→ π−π+π+ decays are compared, providing information about the mechanisms for the hadron formation in these decays. [graphic not available: see fulltext]