Mixed QCD-QED corrections to DGLAP equations

Understand

We study the mixed effect of QCD and QED corrections to the evolution of parton distribution functions (PDFs).

• The Altarelli-Parisi splitting functions are extended to one order higher in QED, reaching ${\cal O}(\alpha \, \alpha_S^2)$ accuracy.
• This also involves extending DGLAP equations to include charge separation effects, that are ignored for pure QCD corrections.
• Besides that, these effects are crucial for the determination of the photon distribution, which plays an increasingly important role in nowadays phenomenological analysis.