Muon and tau anomalies updated
Abstract
We present a new independent evaluation of the hadronic vacuum polarization contributions alhad(l.o)=(1/2)(g-2)lhad(l.o) to the anomalous magnetic moment (anomaly) of the muon and tau leptons using tau-decays and e+e- data. The alone theoretical input used for describing the high-energy region not accessible experimentally is perturbative QCD plus (negligible) additional effects due to the QCD vacuum condensates. We obtain: amuhad(l.o)= 7020.6(75.6)10-11 and atauhad(l.o)= 353.6(3.8)10-8, which we compare with previous determinations. Our analysis leads to the Standard Model (SM) prediction: amuSM=116~591~846.9(78.9)10-11.Confronting amuSM with the recent BNL measurement leads to amunew= amuexp-amuSM=176(170)10-11. Combined with the mean existing determinations of amuhad(l.o), this leads to the conservative range: -42 < amunew1011 < 413 at 90% CL, from which we derive conservative lower bounds on the scales of some new physics. We also update our old predictions of the SM contributions to atau. Including QED to sixth order, higher order hadronic and electroweak contributions, we obtain atauSM=117 755(7)10-8, waiting for a future precise measurement of atau.
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