Abstract
We compute mixed QCD-weak corrections to inclusive Higgs production at the LHC from the partonic process ggto Hqoverline{q} . We start from the UV- and IR-finite oneloop weak amplitude and consider its interference with the corresponding one-loop QCD amplitude. This contribution is a mathcal{O}left({alpha}_salpha right) correction to the leading-order gluon-fusion cross section, and was not numerically assessed in previous works. We also compute the cross section from the square of this weak amplitude, suppressed by mathcal{O}left({alpha}^2right) . Finally, we consider contributions from the partonic process gq → Hq, which are one order lower in αs, as a reference for the size of terms which are not enhanced by the large gluon luminosity. We find that, given the magnitude of the uncertainties on current state-of-the-art predictions for Higgs production, all contributions computed in this work can be safely ignored, both fully inclusively and in the boosted Higgs regime. This result supports the approximate factorisation of QCD and weak corrections to that process.
Highlights
Argument that mixed QCD-weak effects on the inclusive Higgs production cross section are well approximated by combining the purely weak term and the full QCD series in a multiplicative fashion [7]
We address this issue by carrying out the exact inclusive computation of the contribution to mixed QCD-weak corrections from the one-loop partonic subprocess gg → Hqq. We stress that this contribution features one-loop pentagon topologies which appear only in matrix elements with two real emissions, that do not fit in a factorised picture and that have not been assessed before
Our results highlight that considering a subset of higher-order corrections and factorising only a particular combination of initial-state flavours typically yields a large dependence on the factorisation scale. This is especially true for squared amplitude contributions and the boosted regime, for which the chosen fixed scales proportional to the Higgs mass are not well suited in light of the significantly larger collision energies probed
Summary
Weak corrections stemming from the interference with leading QCD production modes are often subject to kinematic suppressions that renders them smaller than what is naively expected from their factorised couplings For this reason, we report the pieces of the cross sections σg(0g,→2)Hqqand σg(−q→1,H2)q built from the square of the amplitudes A(g0g,→2)Hqqand A(g−q→1,2H)q. Z-boson propagator pole, which motivates our use in this computation of the complexmass scheme [11, 12] with finite widths for the internal top quark and unstable weak gauge bosons These diagrams 1d and 1e are ignored when considering their squared contribution to σp(1p,→1)H+X , since in this case they are best accounted for in the narrowwidth approximation as the LO prediction for associated Higgs production, i.e. σg(1g,→1)HZ ( reported in this work). This contribution is analogous to that of the heavy quarks in the two-loop electroweak corrections to Higgs production investigated in ref. [13] and, for this reason, we found it interesting to report our results separately for the processes gg → Hqq, with q ≡ u, d, c, s, and gg → bbH
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