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<p><tt>Theory Center Seminar</tt><tt><br>
</tt><tt>Monday, Nov. 28, 2016</tt><tt><br>
</tt><tt>1:00 p.m. (Coffee at 12:45 p.m.)</tt><tt><br>
</tt><tt>CEBAF Center, Room L102</tt><tt><br>
<br>
Tomas Husek<br>
Charles University in Prague<br>
</tt><tt><br>
</tt></p>
<p><tt> </tt><b>Electromagnetic Transition Form Factor and
Radiative Corrections</b><b> in Decays of Neutral Pions</b><br>
</p>
<tt>In this talk I present the two-hadron saturation (THS) scenario
for the PVV correlator<br>
and apply it to two important processes of the low energy hadron
physics: the Dalitz <br>
decay of $\pi</tt><tt><sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>0</sup></tt><tt>$
and $\pi</tt><tt><sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>0</sup></tt><tt>\to
e^+e^-$. Experimental and theoretical results on the rare <br>
decay $\pi</tt><tt><sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>0</sup></tt><tt>\to
e^+e^-$ are briefly summarized. The notorious $3.3\,\sigma$
discrepancy <br>
between the SM prediction and the experimental value provided by
KTeV collaboration is <br>
discussed in the view of a complete set of NLO QED radiative
corrections. The important <br>
contribution of analytical two-loop QED corrections together with
the bremsstrahlung <br>
contribution beyond the soft-photon approximation are reviewed.
Using the leading <br>
logarithm approximation, the possible contribution of QCD
corrections is estimated. <br>
The discrepancy under discussion then reduces down to
$1.8\,\sigma$. The obtained <br>
results can also be used in a theoretical calculation of the
hadronic light-by-light <br>
scattering contribution to the $g-2$ type experiments.</tt>
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