Pion light-cone distribution amplitude from the pion electromagnetic form factor

Cheng, Shan; Khodjamirian, Alexander; Rusov, Aleksey V.

Abstract

We suggest to probe the pion light-cone distribution amplitude, applying a dispersion relation for the pion electromagnetic form factor. Instead of the standard dispersion relation, we use the equation between the spacelike form factor FπðQ2Þ and the integrated modulus of the timelike form factor. For FπðQ2Þ, the QCD light-cone sum rule with a dominant twist-2 term is used. Adopting for the pion twist-2 distribution amplitude a certain combination of the first few Gegenbauer polynomials, it is possible to fit their coefficients a2;4;6;::. (Gegenbauer moments) from this equation, employing the measured pion timelike form factor. For the exploratory fit we use the data of the BABAR collaboration. The results definitely exclude the asymptotic twist-2 distribution amplitude. Also the model with a single a2 ≠ 0 is disfavored by the fit. Considering the models with an>2 ≠ 0, we find that the fitted values of the second and fourth Gegenbauer moments cover the intervals a2ð1 GeVÞ¼ð0.22–0.33Þ, a4ð1 GeVÞ¼ð0.12–0.25Þ. The higher moments starting from a8 are consistent with zero, albeit with large uncertainties. The spacelike pion form factor obtained in two different ways, from the dispersion relation and from the light-cone sum rule, agrees, within uncertainties, with the measurement by the Jefferson Lab Fπ collaboration.

Citation

Cheng, S., Khodjamirian, A., & Rusov, A. V. (2020). Pion light-cone distribution amplitude from the pion electromagnetic form factor. Physical Review D, 102(7), Article 074022. https://doi.org/10.1103/physrevd.102.074022

• Journal Article Type: Article
• Acceptance Date: Sep 23, 2020
• Online Publication Date: Oct 26, 2020
• Publication Date: 2020-10
• Deposit Date: Nov 11, 2020
• Publicly Available Date: Nov 11, 2020
• Journal: Physical Review D
• Print ISSN: 2470-0010
• Electronic ISSN: 2470-0029
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 102
• Issue: 7
• Article Number: 074022
• DOI: https://doi.org/10.1103/physrevd.102.074022
• Public URL: https://durham-repository.worktribe.com/output/1257400