  We find an argument related to the existence of a Z_2-symmetry for the
renormalization group flow derived from the bare Yang-Mills Lagrangian, and
show that the cancellation of the vacuum energy may arise motivated both from
the renormalization group flow solutions and the effective Yang-Mills action.
In the framework of the effective Savvidy's action, two Mirror minima are
allowed, with exactly equal and hold opposite sign energy densities. At the
cosmological level, we explore the stability of the electric and magnetic
attractor solutions, both within and beyond the perturbation theory, and find
that thanks to these latter the cancellation between the electric and the
magnetic vacua components is achieved at macroscopic space and time
separations. This implies the disappearance of the conformal anomaly in the
classical limit of an effective Yang-Mills theory. In this picture, the
tunneling probability from the Mirror vacua to the other vacua is exponentially
suppressed in the quantum non-thermal state --- similarly to what happens for
electroweak instantonic tunneling solutions. Specifically, we show that, in a
dynamical Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmological background,
the Nielsen-Olsen argument --- on the instability of uniform chromo-electric
and chromo-magnetic Mirror vacua --- is subtly violated. The chromo-magnetic
and chromo-electric uniform vacua are unstable only at asymptotic times, when
the attractor to a zero energy density is already reached. The two vacua can
safely decay into one anisotropic vacuum that has zero energy-density. We also
discover a new surprising pattern of solitonic and anti-solitonic space-like
solutions, which are sourced by the Yang-Mills dynamics in FLRW. We dub such
non-perturbative configurations, which are directly related to dynamical
cancellation mechanism of the vacuum energy, as {\it chronons}, or
$\chi$-solutions.
