# Dortmund 2021 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

# 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 factor — Shan Cheng^{1}, Alexander Khodjamirian^{2}, and •Aleksey Rusov^{2} — ^{1}Hunan University, Changsha, China — ^{2}Universität 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 a_{2,4,6,...} (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 a_{2}≠ 0 is disfavoured by the fit. Considering scenarios with a_{n>2}≠ 0, we find that the fitted values of the second and fourth Gegenbauer moments cover the intervals a_{2} (1 GeV) = (0.22 − 0.33) , a_{4} (1 GeV) = (0.12 − 0.25) . The higher moments starting from a_{8} are consistent with zero, albeit with large uncertainties.