Towards the five-loop Beta function for a general gauge group
  We present analytical results for the $N_f^4$ and $N_f^3$ terms of the five-loop Beta function, for a general gauge group. While the former term agrees with results available from large-$N_f$ studies, the latter is new and extends the value known for SU(3) from an independent calculation. 
Thomas Luthe, Andreas Maier, Peter Marquard and York Schroder
hep-ph