Hadronic top-quark pair-production with one jet and parton showering

TL;DR

Addresses the need for accurate, fully exclusive predictions for top-quark pair production in association with a jet at hadron colliders. It develops and validates an NLO QCD calculation for ttbar+jet merged with parton showers using the POWHEG BOX, including spin-correlated top decays. The study shows that parton showering can substantially modify hadronic charge asymmetries, especially in low-pT regions, while many inclusive distributions remain robust. The work provides a public implementation with options for further improvements and extensions to related processes.

Abstract

We present a calculation of heavy-flavor production in hadronic collisions in association with one jet matched to parton shower Monte Carlo programs at next-to-leading order in perturbative QCD. Top-quark decays are included and spin correlations in the decay products are taken into account. The calculation builds on existing results for the radiative corrections to heavy-quark plus one jet production and uses the POWHEG BOX for the interface to the parton shower programs PYTHIA or HERWIG. A broad phenomenological study for the Large Hadron Collider and the Tevatron is presented. In particular we study---as one important sample application---the impact of the parton shower on the top-quark charge asymmetry.

Figures (14)

• Figure 1: The differential cross sections as function of the transverse momentum $p_{\rm T}^{\;t}$ (upper panel) and of the ${t\bar{t}}$-pair invariant mass $m_{{t\bar{t}}}$ (lower panel), at the Tevatron ($\sqrt{s}=1.96$ TeV).
• Figure 2: The differential cross sections as function of the ${t\bar{t}}$-pair azimuthal separation $\Delta\phi_{t \bar{t}}$ and transverse momentum $p_{\rm T}^{{t\bar{t}}}$, at the Tevatron ($\sqrt{s}=1.96$ TeV).
• Figure 3: The differential cross sections as function of the hardest jet transverse momentum and rapidity at the Tevatron ($\sqrt{s}=1.96$ TeV).
• Figure 4: The differential cross sections as function of the azimuthal distance of the hardest jet from the ${t\bar{t}}$-pair (upper panel) and as a function of the transverse momentum of the system made by ${t\bar{t}}$-pair and the hardest jet (lower panel) at the Tevatron ($\sqrt{s}=1.96$ TeV).
• Figure 5: The differential cross sections as function of the next-to-hardest jet transverse momentum and rapidity at the Tevatron ($\sqrt{s}=1.96$ TeV).