The attached document presents the single variable distributions in data for a signal-like (or signal enhanced) sample and a background-like (or background enhanced) sample.  Also included to reference are the signal and background distributions in simulation.  The similarity between the two shows the consistency of the gaussian process regression - the signal and background definitions in simulation do in fact define the characteristics of the signal-like and background-like samples in the data.  Moreover, these characteristics agree with physical expectation (prompt photons being isolated, single electromagnetic energy depositions).