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

Journal Article · Fri Mar 15 04:00:00 EDT 2013 · Physics of Atomic Nuclei

DOI:https://doi.org/10.1134/S106377881302004X· OSTI ID:22156402

We revisit F{sub {pi}}(Q{sup 2}) and F{sub P{gamma}}(Q{sup 2}), P = {pi}, {eta}, {eta} Prime , 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{sup 2} {>=} 5-6 GeV{sup 2}, the accuracy of the method increasing with Q{sup 2} in this region. For the pion elastic form factor, the well-measured data at small Q{sup 2} give a hint that the LD limit may be reached already at relatively low values of momentum transfers, Q{sup 2} Almost-Equal-To 4-8 GeV{sup 2}; we therefore conclude that large deviations from LD in the region Q{sup 2} = 20-50 GeV{sup 2} seem very unlikely. The data on the ({eta}, {eta} Prime ) {yields} {gamma}{gamma}* form factors meet the expectations from the LD model. However, the BaBar results for the {pi}{sup 0} {yields} {gamma}{gamma}* form factor imply a violation of LD growing with Q{sup 2} even at Q{sup 2} Almost-Equal-To 40 GeV{sup 2}, at odds with the {eta}, {eta} Prime case and with the general properties expected for the LD sum rule.

• OSTI ID: 22156402
• Journal Information: Physics of Atomic Nuclei, Journal Name: Physics of Atomic Nuclei Journal Issue: 3 Vol. 76; ISSN 1063-7788; ISSN PANUEO
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCURACY
DUALITY
FORM FACTORS
MOMENTUM TRANSFER
PIONS
QUANTUM CHROMODYNAMICS
SUM RULES