The Top Cross Section in Hadronic Collisions

TL;DR

The paper reevaluates the hadronic ttbar production cross section, comparing traditional NLO results with soft-gluon resummation using a new minimal prescription. It demonstrates that resummation and Coulomb threshold corrections contribute at most about 1% to the cross section, and provides a detailed uncertainty analysis driven by scale choices, PDFs, and αs. The authors report a precise Tevatron benchmark of σ(mt=175 GeV)=4.75^{+0.73}_{-0.62} pb, and give corresponding predictions for other mt values and collider energies, including LHC forecasts. This work solidifies the SM prediction as a robust baseline for probing new physics in top-quark production.

Abstract

We reexamine the top quark production cross section at the Tevatron and LHC, in the light of recent progress on the resummation of logarithmic soft gluon corrections. We find that resummation effects are much smaller than previously thought. We also compute Coulombic threshold effects, and find them negligible. We update the discussion of uncertainties due to scale dependence, the value of the strong coupling constant, and the parton density parametrization. Our current best estimate of the top production cross section at the Tevatron and its error is $σ(\mt=175\,{\rm GeV})=4.75{+0.73\atop-0.62}$.

Figures (7)

• Figure 1: Contribution of gluon resummation at order $\alpha s$α_s$^4$ and higher, relative to the NLO result, for the individual subprocesses and for the total, as a function of the top mass in $p\bar{p}$ collisions at 1.8 TeV.
• Figure 2: Contribution of gluon resummation at order $\alpha s$α_s$^4$ and higher, relative to the NLO result, for the individual channels and for the total, as a function of the CM energy in $pp$ collisions.
• Figure 3: Contribution of Coulomb effects at order $\alpha s$α_s$^4$ and higher, relative to the NLO result, for the individual channels and for the total, as a function of the CM energy in $p\bar{p}$ collisions.
• Figure 4: Scale dependence of the top cross section at the Tevatron. Dotted lines are the $\mu_{\rm F}$ dependence at fixed $\mu_{\rm R}$, dashed lines are the $\mu_{\rm R}$ dependence at fixed $\mu_{\rm F}$, and solid lines are obtained by the simultaneous variation of $\mu_{\rm R}$ and $\mu_{\rm F}$.
• Figure 5: Top cross section as a function of $\alpha s$α_s$(M_{\rm Z})$. The dotted line does not include the variation of the parton densities due to the change in $\alpha s$α_s$$.