  The violation of non-Abelian Bianchi identity is equal to 8 Abelian monopole
currents of the Dirac type satisfying Abelian conservation rules kinematically.
There exist magnetic $U(1)_m^8$ symmetries in non-Abelian $SU(3)$ QCD. When the
magnetic $U(1)_m^8$ symmetries are broken spontaneously, only states which are
invariant under all $U(1)_e$ subgroups of $SU(3)$ can exist as a physical
state. Such states are $SU(3)$ singlets. The QCD vacuum in the confinement
phase is characterized by one long percolating monopole loop running over the
whole lattice volume in both quenched and full QCD. The long loop in full QCD
is on average a few times longer in comparison with that in quenched QCD case.
Surprisingly, the monopole behaviors in full QCD seem independent of the bare
quark mass suggesting irrelevance of Abelian monopoles to the chiral symmetry
breaking mechanism.
  Existence of such Abelian magnetic monopoles in the continuum limit is
studied in detail in $SU(3)$ by means of a block spin transformation of
monopoles and the inverse Monte-Carlo method. The monopole density $\rho$ and
the infrared effective monopole action $S(k)$ of $n$ blocked monopoles are
determined for $a(\beta)=(0.04\sim 2)$fm and $n=1\sim 12$ blockings on $48^4$
lattice in quenched QCD and for $a(\beta)=0.0846(7)$fm and $n=1\sim 24$ on
$96^4$ in full QCD at $m_\pi=146$MeV. Originally $\rho$ and $S(k)$ are a
two-point function of $a(\beta)$ and the number of times of the blocking
transformation $n$. However, both are found to be a function of $b=na(\beta)$
alone in the quenched QCD which suggests the existence of the continuum limit.
In the full QCD, the renormalization flow is observed similarly but the scaling
is not yet proved. The distributions of the long loops show that monopole
condensation occurs due to the entropy dominance over the energy for all $b$
considered.
