Corrections of to the decay of the Z boson into bottom quarks

Abstract

For the vertex corrections to the partial decay rate Γ(Z → bb) involving the top quark only the leading terms of order αα s in the 1/M t expansion are known. In this work we compute the missing next-to-leading corrections. Thus at O(αα s ) the complete corrections to the decay of the Z boson into bottom quarks are at hand.

The four-loop DRED gauge β-function and fermion mass anomalous dimension for general gauge groups

“…The general result for the two-loop order β e is known [1] and for the three-loop order contributions we find (generalising the QCD results from Ref. [2], using a similar calculational setup to the one applied in [1,2], which relies on the computer programs QGRAF [15], q2e, exp [16,17] and MINCER [18]): …”

Decoupling constant for α s and the effective gluon-Higgs coupling to three loops in supersymmetric QCD

“…The rules of asymptotic expansion (see, e.g., Ref. [24]) are applied on a diagrammatic level using exp [25,26] and finally we evaluate the resulting vacuum integrals which (after asymptotic expansion) only contain a single scale with the help of the package MATAD [27]. The automated setup allows us to perform the calculation for general gauge parameter ξ. Whereasζ 1 ,ζ 3 and ζ 3 individually depend on ξ it drops out in the combination for ζ αs which serves as a welcome check for our calculation.…”

Erratum: Higgs Boson Mass in Supersymmetry to Three Loops [Phys. Rev. Lett.100, 191602 (2008)]

“…[25]. The various diagram topologies are identified and transformed to FORM [26] with the help of q2e and exp [27,28]. The program exp is also used in order to apply the asymptotic expansion (see, e.g., Ref.…”