Improved Predictions for Higgs Q_T at the Tevatron and the LHC

TL;DR

The paper tackles the accuracy of Higgs transverse momentum distributions in gluon fusion at hadron colliders by refining the resummed plus fixed-order matching to ${ m O}(\alpha_s^4)$. It enhances the ResBos framework to produce smoother high-$Q_T$ behavior and larger total cross sections than NLO, including Breit-Wigner effects. The study demonstrates noticeable enhancements in the azimuthal lepton separation and provides PDF and scale uncertainty assessments across Tevatron and LHC energies. These improvements bolster the predictive power for Higgs searches by delivering more reliable kinematic modeling of Higgs production and decay.

Abstract

The search for the Higgs boson at the Tevatron and the LHC relies on detailed calculations of the kinematics of Higgs boson production and decay. In this paper, we improve the calculation of the distribution in transverse momentum, $Q_T$, of the Higgs boson in the gluon fusion production process, $gg\to H$, by matching the resummed distribution at small $Q_T$ with the ${\cal O}(α_{s}^4)$ fixed-order perturbative calculation at high $Q_T$ in the ResBos Monte Carlo program. The distribution is higher at large $Q_T$ than with the old ${\cal O}(α_{s}^3)$ fixed-order perturbative calculation, and the matching with the resummed calculation is much smoother. The total cross section is also increased, more in line with next-to-next-to-leading-order calculations. We also study the effect of the new calculation on the distribution of $Δφ_{\ell\ell}$ in the overall process $gg\to H\to W^{+} W^{-}\to\ell^{+}\ell^{-}ν\barν$, and the effect of PDF uncertainties on the distributions at the Tevatron and the LHC.

Figures (10)

• Figure 1: The total cross section for $gg\to HX$ at the LHC and the Tevatron using the updated ResBos program with CTEQ6.6M PDFs. We consider 7 TeV, $10$ TeV and $14$ TeV c.m. energy at the LHC and $1.96$ TeV c.m. energy at Tevatron. The NLO predictions from ResBos and Higlu programs are also shown.
• Figure 2: The ratio of the total cross section of $gg\to H$ predicted from the resummation calculation to that from NLO calculations at the 7 TeV, 10 TeV and 14 TeV LHC and the Tevatron.
• Figure 3: Transverse momentum, $Q_T$, of the SM Higgs boson at the Tevatron. The black dashed lines and cyan lines are the calculations when matching at high $Q_T$ to the ${\cal O}(\alpha_{s}^{3})$ and ${\cal O}(\alpha_{s}^{4})$ fixed-order perturbative contributions, respectively, and the bands reflect the PDF uncertainties..
• Figure 4: The same as Fig. \ref{['fig:pt_tev']}, but for the SM Higgs boson at the 7 TeV, 10 TeV and 14 TeV LHC.
• Figure 5: The average of $Q_T$ (in the region of $0\le Q_T\le 200$ GeV) of the Higgs boson at the 7 TeV, 10 TeV and 14 TeV LHC and the Tevatron.