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Hadronic production of a Higgs boson in association with two jets at ...

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1.4. Effective coupl<strong>in</strong>g between gluons and a <strong>Higgs</strong> <strong>in</strong> the limit <strong>of</strong> aheavy top quark 27These calcul<strong>at</strong>ions have been confirmed by calcul<strong>at</strong>ion <strong>of</strong> s<strong>of</strong>t terms to N 3 LO accuracy[90,91].When more partons are considered <strong>in</strong> the f<strong>in</strong>al st<strong>at</strong>e top mass effects becomemore pronounced. It has been shown th<strong>at</strong> top and bottom quark mass effects canplay an important role [92] <strong>in</strong> devi<strong>at</strong>ions from the effective theory results [93,94] for<strong>Higgs</strong> plus jet calcul<strong>at</strong>ions <strong>at</strong> NLO. We discuss the role <strong>of</strong> additional <strong>jets</strong> further(<strong>with</strong> an emphasis on <strong>two</strong> <strong>jets</strong>) <strong>in</strong> section 1.5.1.4.2 φ, φ † splitt<strong>in</strong>g <strong>of</strong> the Effective LagrangianWhen we look <strong>at</strong> a simple <strong>Higgs</strong> plus gluon helicity amplitude <strong>at</strong> tree-level a h<strong>in</strong>t <strong>of</strong>structure jumps out <strong>at</strong> us,A (0)4 (φ, 1 − , 2 + , 3 − , 4 + ) =〈13〉 4〈12〉〈23〉〈34〉〈41〉 + [24] 4[12][23][34][41] . (1.56)Here we have used the sp<strong>in</strong>or helicity formalism, which is described <strong>in</strong> Appendix A.Eq. (1.56) has a clear structure, if momentum were conserved amongst the gluons(p H → 0) then the <strong>two</strong> terms would be conjug<strong>at</strong>es <strong>of</strong> each other. With this <strong>in</strong> m<strong>in</strong>dwe make the follow<strong>in</strong>g def<strong>in</strong>itions, [95],φ =(H + iA), φ † =2(H − iA). (1.57)2Here A is a massive pseudo-scalar. We also wish to divide the gluon field strengthtensor G µν <strong>in</strong>to self-dual (SD) and anti-self dual (ASD) pieces,G µνSD = 1 2 (Gµν + ∗ G µν ) G µνASD = 1 2 (Gµν − ∗ G µν ), (1.58)<strong>with</strong>∗ G µν = i 2 ǫµνρσ G ρσ . (1.59)In terms <strong>of</strong> these def<strong>in</strong>itions the Lagrangian takes the follow<strong>in</strong>g form,][HtrG µν G µν + iAtrG ∗ µνG µνL <strong>in</strong>tH,A = C 2= C[]φtrG SD µν G µ,νSD + φ† trG ASD µν G µ,νASD. (1.60)

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