[Primex2] abstract for the Chiral Dynamics-2015

[gasparan at jlab.org]

  Dear Primex-II collaborators,

 The next Chiral Dynamics international workshop is planned to be
 held in June of this year in Italy. We better to present our results
 (preliminary, most likely at this important workshop for our field.

 I put together an abstract for this workshop, it is copied below
 (for some reasons email doesn't work when it is in the attachment).

 Please take a look and email me your comments/suggestions before
 this Wednesday evening. I intend to submit it sometime on Thursday.

 Thank you,
 Ashot

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Neutral Pion Radiative Decay Width Precision Measurement at Jefferson Lab

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 spontaneous chiral symmetry breaking effect (chiral
anomaly) in QCD. Theoretical activities in this domain over the last years
resulted in a high precision (1% level) prediction for the
π0→γγ decay width. The PrimEx collaboration at
Jefferson Lab 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), 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.
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.
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