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Lifetime Measurement of the pi^0 Meson and the QCD Chiral Anomaly

The π0 → γγ decay rate is dominated by the chiral anomaly with 4.1± 1.0 % isospin breaking chiral corrections(proportional to the mass difference of the up and down quarks). A new measurement at Jefferson Lab using the Primakoff effect(PrimEx) is presented with a total error of 3.0%. Great care was taken to reduce systematic errors; this was checked with pair production and Compton scattering measurements. The result is consistent with previous experiments and the predicted value.