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The European Physical Journal C

, Volume 66, Issue 1–2, pp 127–136 | Cite as

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. ZhangEmail author
Regular Article - Theoretical Physics

Abstract

We revisit the procedure for comparing the π π 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 τ π π 0 ν τ branching fraction measurement and its prediction using the isospin-breaking-corrected e + e π + 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.

Keywords

Spectral Function Radiative Correction Pion Form Factor Hide Local Symmetry Conserve Vector Current 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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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
    Email author
  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

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