Orateur
Johann Kuehn
(KIT)
Description
We compute, for the first time, the order alpha_s^4 contribution to the
singlet Adler function for the case of a genereric colour gauge group.
Giving access to the terms proportional to the squared sum of the quark
charges, this result completes the alpha_s^4 corrections to the familiar
R-ratio as measured in electron-positron annihilation. Adopting the colour
factors to the U(1) group, the full five-loop QED beta-function is
completed. An independent calculation leads to the singlet contribution
of order alpha_s^4 to the Gross-Llewellyn Smith sum rule. Relating Adler
function and sum rule through the generalized Crewther relation leads
to two non-trivial constrains which are indeed fullfilled. This cross
check gives additional confidence in the correctness of this highly
complicated calculation.
Auteur principal
Johann Kuehn
(KIT)
