The hadronic contribution to (g-2) of the muon

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dc.creatorDavier, Michel
dc.date2007-01-19
dc.date2007-01-20
dc.date.accessioned2026-07-07T10:37:46Z
dc.date.available2026-07-07T10:37:46Z
dc.descriptionThe evaluation of the hadronic contribution to the muon magnetic anomaly $a_μ$ is revisited, taking advantage of new experimental data on $e^+e^-$ annihilation into hadrons: SND and CMD-2 for the $π^+π^-$ channel, and \babar for multihadron final states. Discrepancies are observed between KLOE and CMD-2/SND data, preventing one from averaging all the $e^+e^-$ results. The long-standing disagreement between spectral functions obtained from $τ$ decays and $e^+e^-$ annihilation is still present, and not accounted by isospin-breaking corrections, for which new estimates have been presented. The updated Standard Model value for $a_μ$ based on $e^+e^-$ annihilation data is now reaching a precision better than experiment, and it disagrees with the direct measurement from BNL at the 3.3$σ$ level, while the $τ$-based estimate is in much better agreement. The $τ$/$e^+e^-$ discrepancy, best revealed when comparing the measured branching fraction for $τ^- \to π^- π^0 ν_τ$ to its prediction from the isospin-breaking-corrected $e^+e^-$ spectral function, remains a serious problem to be understood.
dc.description9 pages, 7 figures, invited talk at the Tau06 International Workshop, Pisa, September 19-22 2006
dc.identifierhttps://arxiv.org/abs/hep-ph/0701163
dc.identifierhttp://arxiv.org/abs/hep-ph/0701163
dc.identifierNucl.Phys.Proc.Suppl.169:288-296,2007
dc.identifierdoi:10.1016/j.nuclphysbps.2007.03.023
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/180491
dc.subjectHigh Energy Physics - Phenomenology
dc.subjectHigh Energy Physics - Experiment
dc.titleThe hadronic contribution to (g-2) of the muon
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