High precision measurements of the differential cross sections for π0 photoproduction at forward angles for two nuclei, C12 and Pb208, have been performed for incident photon energies of 4.9-5.5GeV to extract the π0→γγ decay width. The experiment was done at Jefferson Lab using the HallB photon tagger and a high-resolution multichannel calorimeter. The π0→γγ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is Γ(π0→γγ)=7. 82±0.14(stat)±0.17(syst)eV. With the 2.8% total uncertainty, this result is a factor of2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.
ASJC Scopus subject areas
- Physics and Astronomy(all)