https://doi.org/10.1140/epjp/s13360-020-01024-0
Regular Article
Nonintegrable threshold singularities of two-point functions in perturbation theory
1
D. V. Skobeltsyn Institute of Nuclear Physics, M. V. Lomonosov Moscow State University, 119991, Moscow, Russia
2
Joint Institute for Nuclear Research, 141980, Dubna, Russia
3
Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090, Vienna, Austria
4
Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tre, Via della Vasca Navale 84, 00146, Roma, Italy
Received:
9
October
2020
Accepted:
13
December
2020
Published online:
19
January
2021
In perturbation theory, the spectral densities of two-point functions develop nonintegrable threshold singularities at higher orders. In QCD, such singularities emerge when calculating the diagrams in terms of the pole quark mass, and they become stronger when one rearranges the perturbative expansion in terms of the running quark mass. In this paper, we discuss the proper way to handle such singularities.
© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2021
