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Subject: The Neutral Pion Life Time: Final Result from the PrimEx Experiments
Speaker:    Ashot Gasparian
NC A&T State University for the PrimEx Collaboration
Date: Friday, February 8, 2019
Time: 11:00 a.m.
Place: CEBAF Center Auditorium
Abstract:The neutral pion is the lightest strongly interacting particle in Nature. Therefore, the properties of π0 decay are especially sensitive to the underlying fundamental symmetries of quantum chromodynamics (QCD). In particular, the π0 → γγ decay width is primarily defined by the chiral anomaly, a fundamental symmetry breaking effect in QCD. Theoretical activities in this domain over the past years resulted in a high precision (1% level) prediction for the π0 → γγ decay width. The PrimEx collaboration has developed and performed two new experiments to measure the π0 → γγ decay width with high precision using the Primakoff effect. The published result from the first experiment (PrimEx-I) was a factor of two more precise than the PDG accepted average value, and was in a good agreement with the chiral anomaly prediction. The second experiment (PrimEx-II) was performed in 2010 with a goal of 1.4% total uncertainty to address the next-to-leading-order chiral perturbation theory calculations. The final results from the PrimEx experiments will be presented and discussed in this talk.

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