The European Physical Journal C

, Volume 66, Issue 1, pp 127–136

The discrepancy between τ and e+e spectral functions revisited and the consequences for the muon magnetic anomaly

  • M. Davier
  • A. Hoecker
  • G. López Castro
  • B. Malaescu
  • X. H. Mo
  • G. Toledo Sánchez
  • P. Wang
  • C. Z. Yuan
  • Z. Zhang
Regular Article - Theoretical Physics

DOI: 10.1140/epjc/s10052-009-1219-4

Cite this article as:
Davier, M., Hoecker, A., López Castro, G. et al. Eur. Phys. J. C (2010) 66: 127. doi:10.1140/epjc/s10052-009-1219-4

Abstract

We revisit the procedure for comparing the ππ spectral function measured in τ decays to that obtained in e+e annihilation. We re-examine the isospin-breaking corrections using new experimental and theoretical input and find improved agreement between the τππ0ντ branching fraction measurement and its prediction using the isospin-breaking-corrected e+eπ+π spectral function, though not resolving all discrepancies. We recompute the lowest order hadronic contributions to the muon g−2 using e+e and τ data with the new corrections and find a reduced difference between the two evaluations. The new tau-based estimate of the muon magnetic anomaly is found to be 1.9 standard deviations lower than the direct measurement.

Copyright information

© Springer-Verlag / Società Italiana di Fisica 2010

Authors and Affiliations

  • M. Davier
    • 3
  • A. Hoecker
    • 2
  • G. López Castro
    • 4
  • B. Malaescu
    • 3
  • X. H. Mo
    • 1
  • G. Toledo Sánchez
    • 5
  • P. Wang
    • 1
  • C. Z. Yuan
    • 1
  • Z. Zhang
    • 3
  1. 1.Institute of High Energy PhysicsChinese Academy of SciencesBeijingChina
  2. 2.CERNGeneva 23Switzerland
  3. 3.Laboratoire de l’Accélérateur Linéaire, IN2P3/CNRSUniversité Paris-Sud 11OrsayFrance
  4. 4.Departamento de FísicaCinvestavMexicoMexico
  5. 5.Instituto de FísicaUNAMMexicoMexico