2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 2, 747-756
DOI 10.1007/s100529800721

Calculation of infrared-divergent Feynman diagrams with zero mass threshold

J. Fleischer1 - V.A. Smirnov2 - A. Frink3 - J. Körner3 - D. Kreimer3 - K. Schilcher4, - J.B. Tausk3

1 Fakultät für Physik, Universität Bielefeld, D-33615 Bielefeld , Germany (e-mail: fleischer@physik.uni-bielefeld.de)
2 Nuclear Physics Institute of Moscow State University, 119899 Moscow, Russian Federation (e-mail: smirnov@theory.npi.msu.su)
3 Institut für Physik, Universität Mainz, D-55099 Mainz, Germany (e-mail: frink@dipmza.physik.uni-mainz.de)
4 Department of Physics, University of California, San Diego, La Jolla, CA 92093-0319 USA

Received: 22 April 1997 / Published online: 20 February 1998

Abstract
Two-loop vertex Feynman diagrams with infrared and collinear divergences are investigated by two independent methods. On the one hand, a method of calculating Feynman diagrams from their small momentum expansion [1] extended to diagrams with zero mass thresholds [2] is applied. On the other hand, a numerical method based on a two-fold integral representation is used [3], [4]. The application of the latter method is possible by using lightcone coordinates in the parallel space. The numerical data obtained with the two methods are in impressive agreement.


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