  We report a joint experimental and theoretical investigation of the
probability distribution functions (pdf's) of the normal and tangential
(frictional) forces in amorphous frictional media. We consider both the joint
pdf of normal and tangential forces together, and the marginal pdf's of normal
forces separately and tangential forces separately. A maximum entropy formalism
is utilized for all these cases after identifying the appropriate constraints.
Excellent agreements with both experimental and simulational data are reported.
The proposed joint pdf (which appears new to the literature) predicts giant
slip events at low pressures, again in agreement with observations.
