After a brief review of the muon g-2 status, we discuss hypothetical errors in the Standard Model prediction that might explain the present discrepancy with the experimental value. None of them seems likely. In particular, a hypothetical increase of
the hadroproduction cross section in low-energy e+e- collisions could bridge the muon g-2 discrepancy, but it 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 135GeV which, in conjunction with the experimental 114.4GeV 95% CL lower bound, leaves a narrow window for the mass of this fundamental particle.
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.
After a brief 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 contri
bution 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 M_H, the SM Higgs boson mass. That bound is currently M_H < ~ 150GeV (95%CL) based on the preliminary top quark mass M_t = 172.6(1.4)GeV and the recent determination Delta alpha_{rm had}^{(5)}(M_Z) = 0.02768(22), while the direct-search lower bound is M_H > 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 M_H is reduced to about 130GeV which, in conjunction with the experimental lower bound, leaves a narrow window for the mass of this fundamental particle.
