Electroweak and Bottom Quark Contributions to Higgs Boson plus Jet Production

TL;DR

The paper quantifies how electroweak loop corrections and bottom-quark initiated processes in a five-flavour framework modify Higgs boson production in association with a jet, focusing on differential distributions in jet $p_T$ and pseudorapidity. It adopts a Yukawa-hierarchy-aware calculational scheme that preserves relevant monomials in the top and bottom Yukawa couplings and uses $m_b$ running in $y_b$ within the five-flavour PDFs. The main findings show that electroweak loops can reduce the cross section by up to ~14% at the Tevatron and up to ~3% at the LHC in certain kinematic regions, while bottom-quark parton contributions can increase it by up to ~3–3.5%, with the largest effects at low $p_T$ and central $\eta$. These results, together with a dedicated LO approach that respects Yukawa hierarchies, improve high-$p_T$ predictions for Higgs+jet production and are complemented by a public HJET code release for broader use.

Abstract

This paper presents predictions for jet pseudorapidity (eta) and transverse momentum (p_T) distributions for the production of the Standard Model Higgs boson in association with a high-p_T hadronic jet. We discuss the contributions of electroweak loops and of bottom-quark parton processes to the cross section. The latter arise in the five-flavour scheme. Predictions for the Tevatron and the Large Hadron Collider with 10 TeV collision energy are presented. For Higgs boson masses of 120 GeV, 160 GeV and 200 GeV, we find the maximal effects of the electroweak contributions to the Higgs plus jet p_T and eta distribution to be -14 % and -5.3 %, respectively, for the Tevatron, and -3 % and -2 %, respectively, for the LHC. For the maximal contribution of bottom-quark parton processes to the p_T and eta distribution, we find +3 % and + 2.5 %, respectively, for the Tevatron, and +3.5 % and +3 %, respectively, for the LHC. A separate study of the Higgs + b-jet cross section demonstrates that a calculational approach which respects the hierarchies of Yukawa couplings yields a leading order cross section prediction which is more accurate in the high-p_T regime than conventional approaches.

Figures (14)

• Figure 1: QCD contributions to the scattering amplitudes of the partonic subprocesses (a) $gg \to Hg$, (b) $qg \to Hq$, (c) $q\bar{q}\to Hg$ ($q = u,d,s,c$) and (d) $bg\to Hb$ at leading order. The shaded blob represents a quark loop (only top- and bottom loops contribute significantly). The symbol below each graph indicates to which coefficient in the mathematical expressions for the amplitudes (Eqs. (\ref{['gg-amp']}) and (\ref{['q-amp']})) this graph contributes.
• Figure 2: Electroweak loop contributions to the $u g\to H u$ scattering amplitude at leading order, assuming no up-quark Higgs Yukawa coupling. The depicted graphs contribute all to the coefficient $C_{qg}(u)$ in the mathematical expression for the amplitude (Eq. (\ref{['q-amp']})). The contributions look similar for the scattering of other quark flavours.
• Figure 3: Electroweak loop contributions to the $b g\to H b$ scattering amplitude at leading order which do not vanish for $m_b = 0$. The symbol below each graph indicates to which coefficient in the mathematical expression for the amplitude (Eq. (\ref{['b-amp']})) this graph contributes.
• Figure 4: Relative contributions of different parts of the squared matrix element $|{\cal M}_{qg}(b)|^2$ (see Eq. (\ref{['b-amp-sq']})) to the integrated partonic cross section of $bg \to Hb$ as a function of centre-of-mass energy $\sqrt{\hat{s}}$ for $m_H = 120\,\text{GeV}$ and a cut on the scattering angle $10^\circ < \hat{\theta} < 170^\circ$.
• Figure 5: $p_T$ distribution for quark-gluon scattering at the Tevatron: (a) quark parton processes with and without the $b$ quark contributions, with and without electroweak contributions; (b) relative differences to the left panel; (c) contributions to the $b$ quark parton processes. The depicted approximations are described in the main text.