  In view of the discovery of a new boson by the ATLAS and CMS Collaborations
at the LHC, we present an update of the global Standard Model (SM) fit to
electroweak precision data. Assuming the new particle to be the SM Higgs boson,
all fundamental parameters of the SM are known allowing, for the first time, to
overconstrain the SM at the electroweak scale and assert its validity.
Including the effects of radiative corrections and the experimental and
theoretical uncertainties, the global fit exhibits a p-value of 0.07. The mass
measurements by ATLAS and CMS agree within 1.3sigma with the indirect
determination M_H=(94 +25 -22) GeV. Within the SM the W boson mass and the
effective weak mixing angle can be accurately predicted to be M_W=(80.359 +-
0.011) GeV and sin^2(theta_eff^ell)=(0.23150 +- 0.00010) from the global fit.
These results are compatible with, and exceed in precision, the direct
measurements. For the indirect determination of the top quark mass we find
m_t=(175.8 +2.7 -2.4) GeV, in agreement with the kinematic and cross-section
based measurements.
