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+====== TTP97-54 Two-loop QCD corrections to the heavy quark pair production     cross section in e+e- annihilation near the threshold  ======
+   <hidden TTP97-54  Two-loop QCD corrections to the heavy quark pair production     cross section in e+e- annihilation near the threshold  > We present the O(alpha_s) corrections to the cross section for the
+ reaction e+e- --> gamma^* --> Q \bar Q in the energy region close to
+ the threshold. We assume that the energy of the reaction is such that
+ both the perturbative expansion in the strong coupling constant and
+ expansion in the relative velocity of the heavy quarks can be used.
+ We explicitly obtain terms O(alpha_s^2/beta^2, alpha_s^2/beta,
+ alpha_s^2) in the relative correction to the threshold cross section.
+ Using the ideas of asymptotic expansions, we demonstrate how an
+ expansion of Feynman diagrams in the threshold region is constructed.
+ From this analysis we obtain a matching relation between the vector
+ current in full QCD and the quark--antiquark current in NRQCD at
+ leading order in 1/m and the second order in the strong coupling
+ constant.
+ </hidden>
+|**Andrzej Czarnecki and Kirill Melnikov**  |
+|** Phys. Rev. Lett. 80 2531 1998  **  |
+| {{preprints:1997:ttp97-54.pdf|PDF}} {{preprints:1997:ttp97-54.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/9712222|arXiv]]   |
+| |