Abstract
We present results for the two-loop helicity amplitudes entering the NLO QCD corrections to the production of a Higgs boson in association with a Z -boson in gluon fusion. The two-loop integrals, involving massive top quarks, are calculated numerically. Results for the interference of the finite part of the two-loop amplitudes with the Born amplitude are shown as a function of the two kinematic invariants on which the amplitudes depend.
Highlights
Subprocess is very sensitive to modified Yukawa couplings and/or non-SM particles running in the loop, For these reasons the NLO corrections to this process are very important
We present results for the two-loop helicity amplitudes entering the NLO QCD corrections to the production of a Higgs boson in association with a Z-boson in gluon fusion
Top quark mass effects at NLO QCD have been considered in the framework of a 1/mt-expansion in ref. [17], including Padé approximants constructed from expansion terms up to 1/m8t
Summary
The diagrams contributing to the process (2.1) at leading order are shown in figure 1. In our calculation we use the ’t Hooft-Feynman gauge, the diagram involving the exchange of a would-be Goldstone boson G0 needs to be taken into account. We treat all quarks except the top-quark as massless, only top-quark loops contribute in those diagrams where the Higgs boson couples directly to the fermion loop. The leading order amplitude can be expressed in terms of seven form factors [11] containing one-loop three- and four-point functions. Add finite renormalisation terms to restore chiral symmetry in the massless quark limit, see section 2.2.3. The contraction of two -symbols leads to linear combinations of metric tensors which are treated as D-dimensional
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