6533b828fe1ef96bd1288698
RESEARCH PRODUCT
Next-to-next-to-leading order prediction for the photon-to-pion transition form factor
Dieter MüllerBlaženka MelićBlaženka MelićKornelija Passek-kumeričkisubject
Quantum chromodynamicsPhysicsNuclear and High Energy PhysicsParticle physicsPhysicsForm factor (quantum field theory)Order (ring theory)FOS: Physical sciencesConformal mapAstronomy and AstrophysicsDeep inelastic scatteringHigh Energy Physics - PhenomenologyPionHigh Energy Physics - Phenomenology (hep-ph)transition form factor ; conformal operator ; product expansionConformal symmetryOperator product expansionMathematical physicsdescription
We evaluate the next-to-next-to-leading order corrections to the hard-scattering amplitude of the photon-to-pion transition form factor. Our approach is based on the predictive power of the conformal operator product expansion, which is valid for a vanishing $\beta$-function in the so-called conformal scheme. The Wilson--coefficients appearing in the non-forward kinematics are then entirely determined from those of the polarized deep-inelastic scattering known to next-to-next-to-leading accuracy. We propose different schemes to include explicitly also the conformal symmetry breaking term proportional to the $\beta$-function, and discuss numerical predictions calculated in different kinematical regions. It is demonstrated that the photon-to-pion transition form factor can provide a fundamental testing ground for our QCD understanding of exclusive reactions.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2003-07-01 |