Naslov
Next-to-next-to-leading order prediction for the photon-to-pion transition form factor

Autori
Melić, Blaženka ; Muller, D. ; Passek-Kumerički, Kornelija

Izvornik
Physical review. D, Particles and fields (0556-2821) 68 (2003), 1; 014013, 36

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
transition form factor ; conformal operator ; product expansion

Sažetak
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.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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