Towards an amplitude analysis of the decay $Lambda_b^0to pK^-gamma$

The helicity formalism applied to the radiative decay $Lambda_b^0to pK^-gamma$ is presented for the first time in this paper. The aim is to provide the necessary formalism to be able to resolve the resonant $pK^-$ structures at the photon pole by means of an amplitude analysis. Experimental effects, such as resolution, are also discussed.