  The fermions of the Standard Model are integrated out to obtain the effective
Lagrangian in the sector violating P and CP at zero temperature. We confirm
that no contributions arise for operators of dimension six or less and show
that the leading operators are of dimension eight. To assert this we explicitly
compute one such non-vanishing contribution, namely, that with three Z^0, two
W^+ and two W^-. Terms involving just gluons and W's are also considered,
however, they turn out to vanish in the P-odd sector to eighth order. The
analogous gluonic term in the CP-odd and P-even (C-odd) sector is non-vanishing
and it is also computed. The expressions derived apply directly to Dirac
massive neutrinos. All CP-violating results display the infrared enhancement
already found at dimension six.
