English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We compute the four-loop $n_f$ contribution proportional to the quarticCasimir of the QCD cusp anomalous dimension as an expansion for small cuspangle $\phi$. This piece is gauge invariant, violates Casimir scaling, andfirst appears at four loops. It requires the evaluation of genuine non-planarfour-loop Feynman integrals. We present results up to ${\mathcal O}(\phi^4)$.One motivation for our calculation is to probe a recent conjecture on theall-order structure of the cusp anomalous dimension. As a byproduct we obtainthe four-loop HQET wave function anomalous dimension for this color structure.

On the Casimir scaling violation in the cusp anomalous dimension at small angle