Amplitude analysis of the D+ s → π −π +π + decay

Abstract

A Dalitz plot analysis of the D+ s → π −π +π + decay is presented. The analysis is based on proton-proton collision data recorded by the LHCb experiment at a centreof-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 D+ s → ω(782)π + channel in the D+ s → π −π +π + decay. The resonant structures of the D+ s → π −π +π + and D+ → π −π +π + decays are compared, providing information about the mechanisms for the hadron formation in these decays.