Calculation of the R-ratio of $e^{+}{e}^{-}\to$ hadrons at the higher-loop levels

Abstract

The calculation of the R-ratio of electron-positron annihilation into hadrons is discussed. The method, which enables one to properly account for all the effects due to continuation of the spacelike perturbative results into the timelike domain at an arbitrary loop level, is delineated.

Comments: Based on talk given at the 18th Lomonosov Conference on Elementary Particle Physics (24 - 30 August 2017, Moscow, Russia); 7 pages