Elastic and transition form factors of light pseudoscalar mesons from QCD sum rules

Author(s)
I. A. Balakireva, W. Lucha, D. I. Melikhov
Abstract

We revisit F π(Q 2) and F (Q 2), P = π, η, η′,

making use of the local-duality (LD) version of QCD sum rules. We give

arguments that the LD sum rule provides reliable predictions for these

form factors at Q 2 ≥ 5–6 GeV2, the accuracy of the method increasing with Q 2 in this region. For the pion elastic form factor, the well-measured data at small Q 2 give a hint that the LD limit may be reached already at relatively low values of momentum transfers, Q 2 ≈ 4–8 GeV2; we therefore conclude that large deviations from LD in the region Q 2 = 20–50 GeV2 seem very unlikely. The data on the (η, η′) → γγ* form factors meet the expectations from the LD model. However, the BaBar results for the π 0γγ* form factor imply a violation of LD growing with Q 2 even at Q 2 ≈ 40 GeV2, at odds with the η, η′ case and with the general properties expected for the LD sum rule.

Organisation(s)
Particle Physics
External organisation(s)
Anuchin Research Institute and Museum of Anthropology, Universität Wien, Österreichische Akademie der Wissenschaften (ÖAW)
Journal
Physics of Atomic Nuclei
Volume
76
Pages
326-340
No. of pages
15
ISSN
1063-7788
DOI
https://doi.org/10.1134/S106377881302004X
Publication date
03-2013
Peer reviewed
Yes
Austrian Fields of Science 2012
103034 Particle physics
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/elastic-and-transition-form-factors-of-light-pseudoscalar-mesons-from-qcd-sum-rules(f303af24-cf7e-463b-85e1-ed5efc2ab2f9).html