“…The pion vector form factor has been measured in e + e − → π + π − [23,24,25,26,27,28,29] and in τ → π − π 0 ν τ [30,31] and widely studied in the literature [5,6,7,8,32,33,34,35,36,37,38,39] since it enters the description of many physical processes. As it is the main object concerning our analysis, we will thus provide in the following a brief, but detailed review of its calculation following a bottom-up approach according to the fulfillment of unitarity and analyticity constraints.…”