TTP98-32 The Perturbative QCD Potential and the tt-bar Threshold

TTP98-32 The Perturbative QCD Potential and the tt-bar Threshold

TTP98-32 The Perturbative QCD Potential and the tt-bar Threshold

We include the full second-order corrections to the static QCD potential in the analysis of the $t\bar{t}$ threshold cross section. There is an unexpectedly large difference between the QCD potential improved by the renormalization-group equation in momentum space and the potential improved by the renormalization-group equation in coordinate space. This difference remains even at a fairly short distance $1/r \simeq 100$~GeV and its origin can be understood within perturbative QCD. We scrutinize the theoretical uncertainties of the QCD potential in relation to the $t\bar{t}$ threshold cross section. In particular there exists a theoretical uncertainty which limits our present theoretical accuracy of the $t\bar{t}$ threshold cross section at the peak to be $\delta \sigma_peak/\sigma_peak \simgt 6\%$ within perturbative QCD.

M. Jezabek, J.H. Kuehn, M. Peter, Y. Sumino and T. Teubner
Proc. 29th ICHEP' Vancouver, CA, 23-29 July 1998, edited by A. Astbury, D. Axen, Jacob Robinson (World Scientific, Singapore, 1999) Vol.2, 1613-1617.
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