Speaker
Andrey Grozin
(urn:Google)
Description
The three-loop cusp anomalous dimension $\Gamma$ has been calculated analytically, as a function of the Minkowski angle $\phi$,
via harmonic polylogarithms up to weight 5. The color structures
$C_F (T_F n_f)^{L-1} \alpha_s^L$ in $\Gamma$ and the HQET quark field anomalous dimension have been obtained to all orders. At
large $\phi$ the coefficient of $1/(1-z)_+$ in the DGLAP evolution kernel is reproduced. If we introduce an effective coupling $a$
in such a way that the large-$\phi$ result is exactly first order and re-express $\Gamma(\phi)$ via $a$, the resulting expression
does not contain $n_f$ (and has only one color structure at each order). The known relation between $\Gamma(\phi\to i\pi)$ and the
quark-antiquark potential (which follows from conformal invariance) is violated at three loops by a term proportional to
$\beta_0$.
Primary author
Andrey Grozin
(urn:Google)
Co-authors
Dr
Gregory Korchemsky
(Institut de Physique Théorique, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France)
Johannes Henn
(IAS)
Dr
Peter Marquard
(Deutsches Elektronen-Synchrotron, DESY, Platanenallee 6, D15738 Zeuthen, Germany)
