One may wonder why the value of
is a complicated rational fraction while
is so simple. This is because
was introduced precisely to measure the amount of ambiguities of certain integrals, while by contrast,
was
introduced [see Eq. (185)] as an unknown constant entering the relation between the arbitrary scales
on
the one hand, and
on the other hand, which has a priori nothing to do with the ambiguous part of
integrals.