| Abstract: |
After a review of the muon g-2 status, we analyze the
possibility that the present discrepancy between experiment and the
Standard Model (SM) prediction may be due to hypothetical errors in
the determination of the hadronic leading-order contribution to the
latter. In particular, we show how an increase of the hadro-production
cross section in low-energy e+e- collisions could bridge the muon
g-2 discrepancy, leading however to a decrease on the electroweak
upper bound on MH, the SM Higgs boson mass. That bound is currently
MH<˜150GeV (95%CL) based on the preliminary top quark mass
Mt=172.6(1.4)GeV and the recent determination Δ
αhad(5)(MZ) = 0.02768(22), while the direct-search lower
bound is MH > 114.4GeV (95%CL). By means of a detailed analysis we
conclude that this solution of the muon g-2 discrepancy is unlikely in
view of current experimental error estimates. However, if this turns
out to be the solution, the 95%CL upper bound on MH is reduced to
about 130GeV which, in conjunction with the experimental lower bound,
leaves a narrow window for the mass of this fundamental particle.
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