  Granular materials are an important physical realization of active matter. In
vibration-fluidized granular matter, both diffusion and self-propulsion derive
from the same collisional forcing, unlike many other active systems where there
is a clean separation between the origin of single-particle mobility and the
coupling to noise. Here we present experimental studies of single-particle
motion in a vibrated granular monolayer, along with theoretical analysis that
compares grain motion at short and long time scales to the assumptions and
predictions, respectively, of the active Brownian particle (ABP) model. The
results demonstrate that despite the unique relation between noise and
propulsion, granular media do show the generic features predicted by the ABP
model and indicate that this is a valid framework to predict collective
phenomena. Additionally, our scheme of analysis for validating the inputs and
outputs of the model can be applied to other granular and non-granular systems.
