Status of the PrimEx-II Analysis on the $\pi^{0}$ Lifetime Measurement

As the lightest particle in the hadron spectrum, $\pi^{0}$ plays an important role in understanding the fundamental symmetries of QCD. The $\pi^{0}\to \gamma \gamma $ decay is a key test of the QCD predictions based on the chiral anomaly and spontaneous chiral symmetry breaking. Theoretical activities over the last decade have resulted in a high precision (1{\%} level) in the calculations of the decay amplitude of the $\pi^{0}$ into two photons. The experimental measurement of this parameter with a comparable precision will be critical to test these important predictions. The PrimEx collaboration at Jefferson Lab has developed and performed experiments to measure the $\pi ^{0}$ radiative decay width via the Primakoff effect. The published result from the first experimental data (PrimEx-I) has a 2.8{\%} total uncertainty in the $\pi^{0}$ radiative decay width. The second experiment (PrimEx-II) was carried out in fall 2010 with the final goal of 1.4{\%} precision. The status of PrimEx-II data analysis will be presented.