We present a measurement of the $W$-boson mass, $M_W$, using data corresponding to 2.2/fb of integrated luminosity collected in ppbar collisions at $sqrt{s}$ = 1.96 TeV with the CDF II detector at the Fermilab Tevatron. The selected sample of 470126
$Wto e u$ candidates and 624708 $Wtomu u$ candidates yields the measurement $M_W = 80387pm 12$ (stat) $pm 15$ (syst)$ = 80387 pm 19$ MeV$/c^2$ . This is the most precise single measurement of the $W$-boson mass to date.
We summarize and combine direct measurements of the mass of the $W$ boson in $sqrt{s} = 1.96 text{TeV}$ proton-antiproton collision data collected by CDF and D0 experiments at the Fermilab Tevatron Collider. Earlier measurements from CDF and D0 are c
ombined with the two latest, more precise measurements: a CDF measurement in the electron and muon channels using data corresponding to $2.2 mathrm{fb}^{-1}$ of integrated luminosity, and a D0 measurement in the electron channel using data corresponding to $4.3 mathrm{fb}^{-1}$ of integrated luminosity. The resulting Tevatron average for the mass of the $W$ boson is $MW = 80,387 pm 16 text{MeV}$. Including measurements obtained in electron-positron collisions at LEP yields the most precise value of $MW = 80,385 pm 15 text{MeV}$.
We present a search for new phenomena in events with two reconstructed $Z$ bosons and large missing transverse momentum, sensitive to processes $pbar{p}rightarrow X_2X_2 rightarrow Z Z X_1 X_1$, where $X_2$ is an unstable particle decaying as $X_2rig
htarrow ZX_1$ and $X_1$ is undetected. The particles $X_1$ and $X_2$ may be, among other possibilities, fourth generation neutrinos or supersymmetric particles. We study the final state in which one $Z$ boson decays to two charged leptons and the second decays hadronically. In data corresponding to an integrated luminosity of 4.2 fb$^{-1}$ from proton-antiproton collisions recorded by the CDF II detector at the Tevatron, with center-of-mass energy of 1.96 TeV, we find agreement between data and standard-model backgrounds. We calculate 95% confidence level upper limits on the cross section of the process $pbar{p}rightarrow X_2X_2 rightarrow Z Z X_1 X_1$ ranging from 50 fb to 1 pb, depending on the masses of $X_1$ and $X_2$.
