he gluon mother distribution convoluted with the 
<i>g -> q qbar</i> splitting kernel. In practice, simple solutions 
are only feasible if the gluon shape is assumed to be of the form 
<i>g(x) ~ (1 - x)^p / x</i>, where <i>p</i> is an integer power, 
the parameter above. Allowed values correspond to the cases programmed.
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Since the whole framework is approximate anyway, this should be good 
enough. Note that companions typically are found at small <i>Q^2</i>, 
if at all, so the form is supposed to rep