High-precision measurement of the $W$-boson mass with the CDF II detector.

The mass of the $W$-boson ---$M_{W}$--- is one of the fundamental parameters in the standard model of elementary particles and basic interactions. Following the observation, ten years ago, of the Higgs boson, a measurement of $M_{W}$ provides a stringent test of the model. We measured $M_{W}$ using the CDFII detector, with a data set corresponding to $8.8 {fb^{-1}}$ of integrated luminosity of proton-antiproton collisions at 1.96 TeV centre-of-mass energy at the Fermilab Tevaron collider. A sample of approximately four million $W$-boson candidates is used to obtain $M_{W} = 80433.5\pm 6.4(stat) \pm 6.9(syst) = 80433.5 \pm 9.4$ MeV$/c^{2}$, whose precision currently exceeds that of all previous measurements combined. This measurement is in significant tension with the standard model expectation.