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arXiv · 1001.3075

The pion transition form factor and the pion distribution amplitude

S. Noguera·V. Vento
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Abstract

Recent BaBaR data on the pion transition form factor, whose Q^2 dependence is much steeper then predicted by asymptotic Quantum Chromodynamics (QCD), have caused a renewed interest in its theoretical description. We present here a formalism based on a model independent low energy description and a high energy description based on QCD, which match at a scale Q_0. The high energy description incorporates a flat pion distribution amplitude, phi(x)=1, at the matching scale Q_0 and QCD evolution from Q_0 to Q>Q_0. The flat pion distribution is connected, through soft pion theorems and chiral symmetry, to the pion valance parton distribution at the same low scale Q_0. The procedure leads to a good description of the data, and incorporating additional twist three effects, to an excellent description of the data.

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S. Noguera, V. Vento. 2010-01-18. The pion transition form factor and the pion distribution amplitude. https://doi.org/10.1140/epja/i2010-11029-6

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