  After a brief review of the muon g-2 status, we discuss hypothetical errors
in the Standard Model prediction that could explain the present discrepancy
with the experimental value. None of them looks likely. In particular, an
hypothetical increase of the hadroproduction cross section in low-energy e^+e^-
collisions could bridge the muon g-2 discrepancy, but is shown to be unlikely
in view of current experimental error estimates. If, nonetheless, this turns
out to be the explanation of the discrepancy, then the 95% CL upper bound on
the Higgs boson mass is reduced to about 130 GeV which, in conjunction with the
experimental 114.4 GeV 95% CL lower bound, leaves a narrow window for the mass
of this fundamental particle.
