Karlsruhe 2011 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 10: QCD (Theorie) I

T 10.8: Vortrag

Mittwoch, 30. März 2011, 18:30–18:45, 30.23: 10-1

Light-Cone Sum Rules for the π⁰γγ^* Form Factor — •Florian A.C. Porkert¹, Shahin S. Agaev^1,2, Vladimir M. Braun¹, and Nils Offen¹ — ¹Universität-Regensburg, Regensburg, Deutschland — ²Baku State University, Baku, Aserbaidschan

We provide a theoretical update of the calculations for the π⁰γ^*γ form factor in the light-cone sum rule framework, including up to six polynomials in the conformal expansion of the pion distribution amplitude and taking into account twist-six corrections related to the photon emission at large distances. The results are compared with the calculations of the B→π ℓν decay and pion electromagnetic form factors in the same framework. Our conclusion is that the recent BaBar measurements of the form factor at large momentum transfers are π⁰γ^*γ consistent with QCD and with the bulk of the available information on the pion distribution amplitude (DA), although they do suggest that the pion DA may have more structure than usually assumed.