Nonequilibrium production of photons viaπ0→2γin disoriented chiral condensates

We study the production of photons via the nonequilibrium relaxation of a disoriented chiral condensate with the chiral order parameter having a large initial amplitude along the ${\pi }^0$ direction. Assuming the validity of the low-energy coupling of the neutral pion to photons via the U${}_A\mathrm{}\left(1\right)\mathrm{}$ anomalous vertex, we find that for large initial amplitudes along the ${\pi }^0$ direction photon production is enhanced by parametric amplification. These processes are nonperturbative with a large contribution during the nonequilibrium stages of the evolution and result in a distinct distribution of the produced photons and a polarization asymmetry. For initial amplitudes of the ${\pi }^0$ component of the order parameter between 200 and 400 MeV, corresponding to energy densities between 1 and 12 $\mathrm{GeV}/{\mathrm{fm}}^3$, we find a peak in the photon distribution at energies between $\approx 300$ and 600 MeV. We also find polarization asymmetries typically between 5% and 10%. We discuss the potential experimental impact of these results as well as the problems associated with its detection.