Macroscopic Chirality Fluctuations in Heavy Ion Collisions should induce CP forbidden Decays

Understand

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.