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SUMMARY:Muon g−2 and Δα connection - Massimo Passera (INFN Padova)
DTSTART:20210202T160000Z
DTEND:20210202T170000Z
UID:TALK155017@talks.cam.ac.uk
CONTACT:Heribertus Bayu Hartanto
DESCRIPTION:After a brief review of the discrepancy between the Standard M
 odel theory and experimental measurement of the muon magnetic moment anoma
 ly\, a_μ=(g_μ-2)/2\, I will discuss its connection to precision electrow
 eak (EW) predictions via their common dependence on hadronic vacuum polari
 zation effects. The same data for the total e+e-→hadrons cross section\,
  σ_had(s)\, are used as input into dispersion relations to estimate the h
 adronic vacuum polarization contributions\, a_μ^{had\,VP}\, as well as th
 e five-flavor hadronic contribution to the running QED coupling at the Z-p
 ole\, Δα_had(5)(M_Z)\, which enters natural relations and global EW fits
 . The EW fit prediction of Δα_had(5)(M_Z)=0.02722(41) agrees well with 
 Δα_had(5)(M_Z)=0.02761(11) obtained from the dispersion relation approac
 h\, but exhibits a smaller central value suggestive of a larger discrepanc
 y Δa_μ = a_μ^exp - a_μ^SM than currently expected. Postulating that th
 e Δa_μ difference may be due to unforeseen missing σ_had(s) contributio
 ns\, implications for M_W\, sin2θ_eff_lep and M_H obtained from global EW
  fits are investigated. Shifts in σ_had(s) needed to bridge Δa_μ are fo
 und to be excluded above sqrt(s)≳0.7  GeV at the 95% C.L. Moreover\,
  prospects for Δa_μ originating below that energy are deemed improbable 
 given the required increases in the hadronic cross section.
LOCATION:https://cern.zoom.us/j/61144924828?pwd=WDB6QmFCMEZiSEN5Q0k2aklWSj
 k5Zz09
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