Vector fields, flows and Lie groups of diffeomorphisms
Theoretical Physics Division, CERN, 1211 Geneva 23, Switzerland
Received: 25 February 2000 / Published online: 18 May 2000
- © Springer-Verlag 2000
To the memory of G. de Rham, my teacher in mathematics.
The freedom in choosing finite renormalizations in quantum field theories (QFT) is characterized by a set of parameters , which specify the renormalization prescriptions used for the calculation of physical quantities. For the sake of simplicity, the case of a single c is selected and chosen mass-independent if masslessness is not realized, this with the aim of expressing the effect of an infinitesimal change in c on the computed observables. This change is found to be expressible in terms of an equation involving a vector field V on the action's space M (coordinates x). This equation is often referred to as ``evolution equation'' in physics. This vector field generates a one-parameter (here c) group of diffeomorphisms on M. Its flow can indeed be shown to satisfy the functional equation
so that the very appearance of V in the evolution equation implies at once the Gell-Mann-Low functional equation. The latter appears therefore as a trivial consequence of the existence of a vector field on the action's space of renormalized QFT.
Copyright Società Italiana di Fisica, Springer-Verlag 2000