Neutral Pion Decay
Published on Oct 26, 2011in Annual Review of Nuclear and Particle Science14.219
· DOI :10.1146/ANNUREV-NUCL-102010-130426
The study of π0 decay has played an important role in the development of particle physics: The π0→γγ decay provides key insights into the anomaly sector of quantum chromodynamics. In this review, the historical progression of π0 discovery, lifetime measurements, and theory are presented. A new measurement of the π0 radiative width via the Primakoff effect has been made at JLab. The result, Γ(π0→γγ)=7.82±0.14(stat.)±0.17(syst.) eV, is a factor of 2.1 more precise than the currently accepted value, and it is in agreement with the chiral anomaly prediction and with next-to-leading-order chiral perturbation theory calculations. Primakoff experiments at higher energies to measure the η and η′ radiative widths are also discussed.