First Measurements of Inclusive $W$ and $Z$ Cross Sections from Run II of the Fermilab Tevatron Collider

We report the first measurements of inclusive $W$ and $Z$ cross sections times leptonic branching ratios for $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{T}\mathrm{e}\mathrm{V}$, based on their decays to electrons and muons. The data correspond to an integrated luminosity of $72{\mathrm{p}\mathrm{b}}^{-1}$ recorded with the CDF detector at the Fermilab Tevatron. We test $e$-$\mu$ universality in $W$ decays, and we measure the ratio of leptonic $W$ and $Z$ rates from which the leptonic branching fraction $B(W\to \ell \nu )$ can be extracted as well as an indirect value for the total width of the $W$ and the Cabibbo-Kobayashi-Maskawa matrix element, $|V_{cs}|$.

Figure 1

Distributions of $M_T$ for $W\to \mu \nu$ (top) and $M_{e^{+}{e}^{-}}$ for $Z/{\gamma }^{*}\to e^{+}{e}^{-}$ (bottom). The arrows in the $M_{e^{+}{e}^{-}}$ distribution define the mass window.