  In the confined Bethe-Salpeter (BS) methods, the quark propagator is an
entire function. Hence, the imaginary part of the handbag diagram disappears,
leading to a problem of the vanishing parton distribution function (PDF). In
contrast, the direct calculation of the light-cone (LC) momentum distribution
does give a non-vanishing result even in the confined BS framework. We consider
their precise relation and difference, and propose to use the latter as a
practical approach to this problem. Our formalism is general enough to be
applied to various effective models.
