  f large fluctuations of quark chirality occur in heavy ion collisions, they
result in macroscopic CP-odd "spots" of the so called theta-vacua, with a
non-zero $\theta(x)$. We consider particular decays of mesons, CP-forbidden in
the vacuum with zero $\theta$, like $\eta\to \pi\pi$. We evaluate their rates
for such decays near hadronic freezeout. These rates, as well as charge
asymmetries already observed, are proportional to square of the CP-violating
parameter $<\theta^2>$ averaged over the fireball and events. With such input,
we found that the forbidden decay rates are likely to be orders of magnitude
larger than CP-allowed ones. We further estimated that up to about one per mill
of $\eta$ mesons produced in heavy ion collisions should decay in this way. We
further discuss how those can be observed. We argue using STAR data on charge
asymmetries for AuAu and CuCu collisions that the size of CP-odd spots at
freezeout is as large as Cu nuclei: this fortunate fact (not explained so far
by itself) suggests that the two-pion invariant mass is modified by only about
a percent, which is comparable to experimental resolution. If so, we think
experimental observation of these decays is within the reach of current
dataset. If those decays are found, it would confirm that CP-odd interpretation
of charge asyymetry is correct, even without complication related to geometry,
impact parameter or magnetic field induced on the fireball.
