Four-loop cusp anomalous dimension in QED
The 4-loop C F 3 T F n l and 5-loop C F 4 T F n l terms in the HQET field anomalous dimension γ h are calculated analytically (the 4-loop one agrees with the recent numerical result ). The 4-loop C F 3 T F n l and 5-loop C F 4 T F n l terms in the cusp anomalous dimension Γ(φ) are calculated analytically, exactly in φ (the φ → ∞ asymptotics of the 4-loop one agrees with the recent numerical result ). Combining these results with the recent 4-loop d F F n l contributions to γ h and to the small-φ expansion of Γ(φ) up to φ4 , we now have the complete analytical 4-loop result for the Bloch-Nordsieck field anomalous dimension in QED, and the small-φ expansion of the 4-loop QED cusp anomalous dimension up to φ4.
KeywordsEffective Field Theories Perturbative QCD Renormalization Group Wilson, ’t Hooft and Polyakov loops
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