$\Lambda^+_\mathrm{c}$ polarimetry using the dominant hadronic mode

The polarimeter vector field for multibody decays of a spin-half baryon is introduced as a generalisation of the baryon asymmetry parameters. Using a recent amplitude analysis of the $\Lambda^+_\mathrm{c} \to p K^- \pi^+$ decay performed at the LHCb experiment, we compute the distribution of the kinematic-dependent polarimeter vector for this process in the space of Mandelstam variables to express the polarised decay rate in a model-agnostic form. The obtained representation can facilitate polarisation measurements of the $\Lambda^+_\mathrm{c}$ baryon and eases inclusion of the $\Lambda^+_\mathrm{c} \to p K^- \pi^+$ decay mode in hadronic amplitude analyses.