Four-Loop Decoupling Relations for the Strong Coupling
نویسندگان
چکیده
We compute the matching relation for the strong coupling constant within the framework of QCD up to four-loop order. This allows a consistent five-loop running (once the β function is available to this order) taking into account threshold effects. As a side product we obtain the effective coupling of a Higgs boson to gluons with five-loop accuracy.
منابع مشابه
QCD Decoupling at Four Loops s
We present the matching condition for the strong coupling con-tant α (n f) s at a heavy quark threshold to four loops in the modified minimal subtraction scheme. Our results lead to further decrease of the theoretical uncertainty of the evolution of the strong coupling constant through heavy quark thresholds. Using a low energy theorem we furthermore derive the effective coupling of the Higgs b...
متن کاملTHREE-LOOP RUNNING OF THE STRONG COUPLING CONSTANT AND THE MASS OF THE b QUARK IN THE SUPERSYMMETRIC QCD
Supersymmetric extension of the QCD (SQCD) is considered, and the scale dependence of some important parameters, i.e., strong coupling αs and b-quark running mass mb, is studied with the help of three-loop renormalization group equations. Fiveavour QCD is considered as a lowenergy effective theory of SQCD, and two-loop decoupling (threshold) effects are taken into account. Variations in running...
متن کاملRunDec: a Mathematica package for running and decoupling of the strong coupling and quark masses
In this paper the formulae are collected which are needed for the computation of the strong coupling constant and quark masses at different energy scales and for different number of active flavours. All equations contain the state-of-the-art QCD corrections up to threeand sometimes even four-loop order. For the practical implementation Mathematica is used and a package containing useful procedu...
متن کاملRunning of αs in the MSSM with three-loop accuracy
The evolution of the strong coupling constant αs from MZ to the GUT scale is presented, involving three-loop running and two-loop decoupling. Accordingly, the two-loop transition from the MS to the DR scheme is properly taken into account. We find that the three-loop effects are comparable to the experimental uncertainty for αs. PACS. 11.30.Pb Supersymmetry – 12.38.-t Quantum chromodynamics
متن کاملar X iv : h ep - p h / 98 12 48 5 v 3 1 8 Ja n 20 00 Renormalization Group Relations and searching for Abelian Z ′ Boson in the four - fermionic processes
The method of searching for signals of heavy virtual particles is developed. It is based on a renormalization group equation for the low energy effective Lagrangian and the decoupling theorem. As an application, the model independent search for Abelian Z ′ boson in four-fermion processes is analyzed. The basic one-loop renormalization group relation for the parameters of the effective Lagrangia...
متن کامل