A Renormalization Group Improved Calculation of Top Quark Production near Threshold

TL;DR

The top-quark cross section close to threshold in e(+)e(-) annihilation is computed including the summation of logarithms of the velocity at next-to-next- to-leading-logarithmic order in QCD.

Abstract

The top quark cross section close to threshold in $e^+e^-$ annihilation is computed including the summation of logarithms of the velocity at next-to-next-to-leading-logarithmic order in QCD. The remaining theoretical uncertainty in the normalization of the total cross section is at the few percent level, an order of magnitude smaller than in previous next-to-next-to-leading order calculations. This uncertainty is smaller than the effects of a light standard model Higgs boson.

Figures (1)

• Figure 1: The upper panel shows the normalized photon-induced cross section for $t\bar{t}$ at LL order (dotted), NLL order (dashed), and NNLL order (solid) in the 1S mass scheme with $\nu=0.15$, $0.2$, and $0.4$. The lower panel shows the $\nu$ dependence of the contributions in Eq. (\ref{['NNLLcrosssection']}) to $R^{\rm NNLL}(\sqrt{s}=350\,{\rm GeV})$. The $\delta G^k$ contribution is shown by the dotted line, the sum of $\delta G^{\delta,r,{\rm kin}}$ terms by the dot-dashed line, the terms involving $\delta G^c$ by the dashed line, and the sum by the solid line.