Dortmund 2021 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 6: Flavour physics I

T 6.5: Vortrag

Montag, 15. März 2021, 17:00–17:15, Tf

The pion light-cone distribution amplitude from the pion electromagnetic form factorShan Cheng1, Alexander Khodjamirian2, and •Aleksey Rusov21Hunan University, Changsha, China — 2Universität Siegen, Germany

We suggest a new way of probing the pion light-cone distribution amplitude using the dispersion relation for the pion electromagnetic form factor. It relates the spacelike pion form factor, for which the QCD light-cone sum rule is used, with the timelike form factor obtained from the data. Adopting for the pion twist-2 distribution amplitude an ansatz with the first few Gegenbauer polynomials, it is possible to fit their coefficients a2,4,6,... (Gegenbauer moments) from the dispersion relation. For the exploratory fit we use the data of the BaBar collaboration. The results definitely exclude the asymptotic shape of the twist-2 distribution amplitude, also the model with a single a2≠ 0 is disfavoured by the fit. Considering scenarios with an>2≠ 0, we find that the fitted values of the second and fourth Gegenbauer moments cover the intervals a2 (1 GeV) = (0.22 − 0.33) , a4 (1 GeV) = (0.12 − 0.25) . The higher moments starting from a8 are consistent with zero, albeit with large uncertainties.

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