Five-loop accuracy in perturbative QCD

• Applicants: Dr. Konstantin Chetyrkin; Professor Dr. Johann Kühn
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 262491569

• Final Report Year: 2018

Final Report Abstract

The QCD beta function has been evaluated in five loop approximation. This recent calculation can be used to relate measurements of the strong coupling constant at low and high energies with unprecedented precision. Since its first publication this result has been confirmed by three independent calculations and even extended to a general gauge group. A remarkable feature is the surprising smallness of the perturbative terms, characterized by the small deviation from the leading order result. Also the five-loop fermion anomalous dimension for a general gauge group has been obtained in the course in the course of this project. Last not the least the Higgs-Gluon-Gluon coupling has been evaluated to order α^5s , bringing the prediction for the Higgs boson production and decay for a new level of precision. Just after our paper was published in Physical Review Letters we got a congratulation message from one of the founders of the QCD—Professor David Gross.

Publications

• The β-function of Quantum Chromodynamics and the effective Higgs-gluon-gluon coupling in five-loop order, PoS LL2016 (2016) 010
  K. Chetyrkin, P. Baikov and J. Kühn
  
• Five-loop fermion anomalous dimension for a general gauge group from four-loop massless propagators, JHEP 04 (2017) 119
  P. A. Baikov, K. G. Chetyrkin and J. H. Kühn
  
• Five-loop renormalisation of QCD in covariant gauges, JHEP 10 (2017) 179
  K. G. Chetyrkin, G. Falcioni, F. Herzog and J. A. M. Vermaseren
  
• Five-Loop Running of the QCD coupling constant, Phys. Rev. Lett. 118 (2017) 082002
  P. A. Baikov, K. G. Chetyrkin and J. H. Kühn