Pion and nucleon twist -4 structure functions in the limit x->1

The chi -> 1 behavior of the pion and nucleon structure functions is studied here within the framework of the operator product expansion. The work on the twist-4 structure functions is performed in the longitudinal operator basis, which has the advantage that all the exact information known about the operator matrix elements has been used during the transformation into this basis. The simplicity of the twist-4 operator matrix elements is such that it is possible to arrive at power counting arguments for the chi -> 1 behavior in anlogy with the standard counting rules for the twist-2 structure functions. (orig.)