Precise measurement of the W-boson mass with the CDF II detector

TL;DR

This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined.

Abstract

We have measured the W-boson mass MW using data corresponding to 2.2/fb of integrated luminosity collected in proton-antiproton collisions at 1.96 TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined.

Figures (3)

• Figure 1: The $Z \rightarrow \mu \mu$ (top) and $Z \rightarrow ee$ (bottom) mass fits, showing the data (points), the best-fit simulation template (histogram) and the photon-pole contribution (shaded). The arrows indicate the fitting range.
• Figure 2: The distribution of $E / p$ for the $W \rightarrow e \nu$ data (points) and the best-fit simulation (histogram) including the small jet background. The arrows indicate the fitting range used for the electron energy calibration.
• Figure 3: The $m_T$ distribution for muons (top) and the $p_T^\ell$ distribution for electrons (bottom). The data (points) and the best-fit simulation template (histogram) including backgrounds (shaded) are shown. The arrows indicate the fitting range.