The first step in it is called regularization, methods of which were developed by Wilson and 't Hooft.  
One quadruply-eponymous scheme for this procedure is named after Bogoliubov, Parasiuk, Hepp, and Zimmermann, while other schemes for this procedure are the on-shell and minimal-subtraction schemes, and it leads to the effect of running coupling constants. The first step in it is called regularization, methods of which were developed by Wilson and 't Hooft.  This mathematical procedure is made necessary because when one integrates over all possible momenta and energies in the loops of Feynman diagrams for vaccum polarization and self-energy, the integrals are infinite.  FTP, name this procedure used in quantum field theory that absorbs divergent quantities into redefined physical quantities so as to cancel out infinite terms.
One quadruply-eponymous scheme for this procedure is named after Bogoliubov, Parasiuk, Hepp, and Zimmermann, while other schemes for this procedure are the on-shell and minimal-subtraction schemes, and it leads to the effect of running coupling constants.
{renormalization}