June 29, 2015 to July 3, 2015
Europe/Rome timezone

Precision measurement of the neutral pion radiative decay width at Jefferson Lab

Jul 2, 2015, 5:50 PM
Aula Magna (Building E, Polo Fibonacci, Pisa)

Aula Magna

Building E, Polo Fibonacci, Pisa

Talk Goldstone Boson Working Group Parallel Session 6 - Goldstone Boson WG


Ashot Gasparian (North Carolina A&T State University, Greensboro)


The neutral pion is the lightest strongly interacting particle in Nature. Therefore, the properties of $\pi^0$ decay are especially sensitive to the underlying fundamental symmetries of quantum chromodynamics (QCD). In particular, the pi^0 -> gamma gamma decay width is primarily defined by the spontaneous chiral symmetry breaking effect (chiral anomaly) in QCD. Theoretical activities in this domain over the past several years have resulted in a high precision (1% level) prediction for the pi^0 -> gamma gamma decay width. The PrimEx collaboration at Jefferson Lab has developed and performed two new experiments to measure the pi^0 -> gamma gamma decay width with high precision using the Primakoff effect. The published result from the first experiment (PrimEx-I), Gamma(pi^0 -> gamma gamma) = 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. 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 preliminary results from the PrimEx-II experiment will be presented in this talk.

Primary author

Ashot Gasparian (North Carolina A&T State University, Greensboro)

Presentation materials