Effects of QCD Resummation on $W^+h$ and $t\bar b$ Production at the Tevatron

TL;DR

The paper applies Collins-Soper-Sterman soft-gluon resummation to W^+h and t b production at the Tevatron to refine SM predictions. It demonstrates that initial-state QCD resummation modestly enhances production rates by 2–3% over NLO for W^+h and by about 3.5% for t b when m_t=175 GeV, while properly matching to fixed-order results to avoid unphysical results at large Q_T. Final-state radiation is treated at NLO for t b, revealing that radiation effects dominate the kinematics of individual top and bottom quarks, whereas initial-state resummation shapes the t b pair kinematics. These improvements are important for Higgs searches and precise CKM measurements (V_tb) at the Tevatron, particularly in shaping relevant distributions and reducing theoretical uncertainties.

Abstract

The resummation of multiple soft gluon emission affects the production rate and kinematic distributions of $W^+h$ (where h is a Higgs boson) and $t \bar b$ pairs at the Tevatron with $\sqrt{s}=2$ TeV. Using the Collins-Soper-Sterman resummation formalism, the production rate is enhanced over the next-to-leading-order (NLO) prediction by 2-3% for the $W^+h$ process, for Higgs boson masses between 80-120 GeV, and over 3% for the $t\bar b$ process for $m_t=175$ GeV. After resummation, the $t\bar b$ rate changes by 12-13% when $m_t$ is varied by $\pm 5$ GeV. Various kinematic distributions are presented for the individual final state particles and for the pair. The explicit radiation of hard gluons in NLO QCD is included also for the $t\bar b$ final state.

Figures (12)

• Figure 1: The $Q_T$ spectrum for $W^+h$ Events
• Figure 2: The $P_T^h$ spectrum for $W^+h$ Events
• Figure 3: The $y^h$ spectrum for $W^+h$ Events
• Figure 4: The $\Delta y^{W^+h}$ spectrum for $W^+h$ Events
• Figure 5: The $\Delta\phi^{W^+h}$ spectrum for $W^+h$ Events