Speaker
Dr
Daisuke Nomura
(Tohoku University)
Description
We update our Standard Model predictions for g-2 of the muon and for
the hadronic contributions to the running of the QED coupling,
\Delta\alpha^{(5)}_{had}(M_Z^2). Particular emphasis is put on
recent changes in the hadronic contributions from new data in the
2\pi channel and from the energy region just below 2 GeV. In
particular, for the e^+e^- \to \pi^+\pi^- contribution we include
the recent `radiative return' data from KLOE and BaBar. We also
include the recent BaBar data on other exclusive channels. We make a
detailed study of the effect of replacing the measurements of the
inclusive cross section, \sigma(e^+e^- \to hadrons),
by the sum of the exclusive channels in the energy interval
1.43 < \sqrt{s} < 2 GeV, which includes a QCD sum-rule analysis
of this energy region. Our favoured prediction for the muon
anomalous magnetic moment is
(g-2)/2 = (11659182.8 \pm 4.9) \times 10^{-10} which is
3.3 \sigma below the present world-average measurement. We compare
our g-2 value with other recent calculations. Our prediction for the
QED coupling, obtained via \Delta\alpha_{had}^{(5)}(M_Z^2) =
( 276.26 \pm 1.38 ) \times 10^{-4} is \alpha(M_Z^2)^{-1} =
128.944 \pm 0.019.