Matter dependence of the four-loop QCD cusp anomalous dimension: from small angles to all angles

A bstract We compute the fermionic contributions to the cusp anomalous dimension in QCD at four loops as an expansion for small cusp angle. As a byproduct we also obtain the respective terms of the four-loop HQET wave function anomalous dimension. Our new results at small angles provide stringent te...

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Bibliographic Details
Published inThe journal of high energy physics Vol. 2019; no. 5; pp. 1 - 29
Main Authors Brüser, Robin, Grozin, Andrey, Henn, Johannes M., Stahlhofen, Maximilian
Format Journal Article
LanguageEnglish
Published Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2019
Springer Nature B.V
SpringerOpen
Subjects
Classical and Quantum Gravitation
Dependence
Effective Field Theories
Elementary Particles
High energy physics
Perturbative QCD
Physics
Physics and Astronomy
Quantum Field Theories
Quantum Field Theory
Quantum Physics
Regular Article - Theoretical Physics
Relativity Theory
Scattering Amplitudes
String Theory
Wilson, ’t Hooft and Polyakov loops
Wilson, ’t Hooft and Polyakov loops
Effective Field Theories
Scattering Amplitudes
Perturbative QCD
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Summary:A bstract We compute the fermionic contributions to the cusp anomalous dimension in QCD at four loops as an expansion for small cusp angle. As a byproduct we also obtain the respective terms of the four-loop HQET wave function anomalous dimension. Our new results at small angles provide stringent tests of a recent conjecture for the exact angle dependence of the matter terms in the four-loop cusp anomalous dimension. We find that the conjecture does not hold for two of the seven fermionic color structures, but passes all tests for the remaining terms. This provides strong support for the validity of the corresponding conjectured expressions with full angle dependence. Taking the limit of large Minkowskian angle, we extract novel analytic results for certain terms of the light-like cusp anomalous dimension. They agree with the known numerical results. Finally, we study the anti-parallel lines limit of the cusp anomalous dimension. In a conformal theory, the latter is proportional to the static quark-antiquark potential. We use the new four-loop results to determine parts of the conformal anomaly term.
ISSN:1029-8479
1029-8479
DOI:10.1007/JHEP05(2019)186