In:
Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2020, No. 7 ( 2020-07)
Abstract:
We consider QCD corrections to two loops for the polarized amplitudes of $$ q\overline{q} $$ q q ¯ → Z + Higgs boson. First we show how the polarized amplitudes of $$ b\overline{b} $$ b b ¯ → Zh associated with a non-vanishing b -quark Yukawa coupling and a scalar or pseudoscalar Higgs boson h can be built up solely from vector form factors (FF) of properly grouped classes of diagrams, bypassing completely the need of explicitly manipulating γ 5 in dimensional regularization (up to a few “anomalous”, i.e., triangle diagrams). We determine the contributions of the triangle diagrams in the heavy top limit. We present the analytic results of the vector FF and the triangle-diagram contributions to the axial vector FF, which are sufficient for deriving the two-loop QCD amplitudes for $$ b\overline{b} $$ b b ¯ → Zh with a CP-even and CP-odd Higgs boson h . We derive the respective Ward identity for these amplitudes, which are subsequently verified to two-loop order in QCD using these FF. In addition, the FF of a class of corrections to $$ q\overline{q} $$ q q ¯ → ZH proportional to the top-Yukawa coupling are obtained analytically to two-loop order in QCD in the heavy-top limit using the Higgs-gluon effective Lagrangian where the top quark is integrated out. We address a pitfall that occurs when applying the non-anticommutating γ 5 prescription to this class of contributions that has been overlooked so far in the literature. We attribute this issue to the fact that the absence of certain heavy-mass expanded diagrams in the infinite-mass limit of a scattering amplitude with an axial vector current depends on the particular γ 5 prescription in use.
Type of Medium:
Online Resource
ISSN:
1029-8479
DOI:
10.1007/JHEP07(2020)159
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2020
detail.hit.zdb_id:
2027350-2
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