TTP09-09 Completely automated computation of the heavy-fermion corrections to the three-loop matching coefficient of the vector current

TTP09-09 Completely automated computation of the heavy-fermion corrections to the three-loop matching coefficient of the vector current

TTP09-09 Completely automated computation of the heavy-fermion corrections to the three-loop matching coefficient of the vector current

We evaluate the corrections to the matching coefficient of the vector current between Quantum Chromodynamics (QCD) and Non-Relativistic QCD (NRQCD) to three-loop order containing a closed heavy-fermion loop. The result constitutes a building block both for the bottom- and top-quark system at threshold. Strong emphasis is put on our completely automated approach of the calculation including the generation of the Feynman diagrams, the identification of the topologies, the reduction to master integrals and the automated numerical computation of the latter.

 P. Marquard, J.H. Piclum, D. Seidel, M. Steinhauser Phys.Lett. B678 269-275 2009 PDF PostScript arXiv