1998/12/10 by Robin G. Stuart, Stuart, Robin G.
Physics and Astronomy · #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle Detector Development and Performance #Particle physics theoretical and experimental studies #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/9812323
9 pages, LaTeX, uses sprocl.sty, amsmath.sty, amssymb.sty and axodraw.sty. To appear in the Proceedings of the IVth International Symposium on Radiative Corrections (RADCOR98), Barcelona, Spain, 8-12 September, 1998, edited by J. Sola
arxiv created 1998/12/10 · openalex publication_date 1998/12/10 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The complete 2-loop QED contributions to the muon lifetime have been calculated analytically in the Fermi theory. The exact result for the effects of virtual and real photons, virtual electrons, muons and hadrons as well as e+e- pair creation is Delta Gamma^(2)=Gamma0(alpha/pi)2[(156815/5184)-(1036/27)zeta(2) -(895/36)zeta(3)+(67/8)zeta(4) +53zeta(2)ln(2)-(0.042+/-0.002)] where Gamma0 is the tree-level width. This eliminates the theoretical error in the extracted value of the Fermi coupling constant, GF, which was previously the source of the dominant uncertainty. The new value is GF=(1.16637 +/- 0.00001) x 10-5 GeV-2 with the error being entirely experimental. Several experiments are planned for the next generation of muon lifetime measurements and these can proceed unhindered by theoretical uncertainties.