Axial-vector contributions in two-photon reactions: Pion transition form factor and deeply-virtual Compton scattering at NNLO in QCD

Autor: J. Schönleber, A. N. Manashov, Vladimir M. Braun, Sven Moch
Rok vydání: 2021
Předmět:
generalized parton distribution
higher-order
parton: distribution function
symmetry
conformal
Parton
GeV
electron nucleus
distribution amplitude
light cone
COMPASS
High Energy Physics - Phenomenology (hep-ph)
transition [form factor]
distribution amplitude: light cone
Nuclear Experiment
two-photon
Quantum chromodynamics
Physics
parton
distribution function
ddc:530
Form factor (quantum field theory)
Perturbative QCD
quantum chromodynamics
perturbation theory
axial-vector
form factor
transition
higher-order
2
High Energy Physics - Phenomenology
distribution function [parton]
perturbation theory [quantum chromodynamics]
light cone [distribution amplitude]
Particle physics
CERN Lab
accelerator
FOS: Physical sciences
BELLE
Pion
deeply virtual Compton scattering
quantum chromodynamics: perturbation theory
numerical calculations
Pseudovector
form factor: transition
electron nucleon: scattering
Compton scattering
Order (ring theory)
electron nucleon
colliding beams
conformal [symmetry]
530 Physik
scattering [electron nucleon]
symmetry: conformal
High Energy Physics::Experiment
Zdroj: Physical review / D 104(9), 094007 (2021). doi:10.1103/PhysRevD.104.094007
Physical Review
DOI: 10.5283/epub.51736
Popis: Physical review / D 104(9), 094007 (2021). doi:10.1103/PhysRevD.104.094007
Using the approach based on conformal symmetry we calculate the two-loop coefficient function for the axial-vector contributions to two-photon processes in the $\overline{\rm MS}$ scheme. This is the last missing element for the complete next-to-next-to-leading order (NNLO) calculation of the the pion transition form factor $\gamma^\ast\gamma\to \pi $ in perturbative QCD. The corresponding high-statistics measurement is planned by the Belle II collaboration and will allow one to put strong constraints on the pion light-cone distribution amplitude. The calculated NNLO corrections prove to be rather large and have to be taken into account. The same coefficient function determines the contribution of the axial-vector generalized parton distributions to deeply-virtual Compton scattering which is investigated at the JLAB 12 GeV accelerator, by COMPASS at CERN, and in the future will be studied at the Electron Ion Collider EIC.
Published by Inst., Melville, NY
Databáze: OpenAIRE
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