## Ratio Method of Measuring the W Boson Mass

##### Abstract

This dissertation describes an alternative method of measuring the W boson mass in Dzero experiment. Instead of extracting W mass from the fitting of fast Monte Carlo simulations to data as in the standard method, we make the direct fit of the transverse mass between W data and Z data. One of the two electrons from Z boson is treated as a neutrino in the calculation of transverse mass. In ratio method, the best fitted scale factor corresponds to the ratio of W and Z boson mass. Given the precisely measured Z boson mass, W mass is directly fitted from W and Z data. This dissertation demonstrates that ratio method is a plausible method of measuring the W boson mass. With the Dzero Run IIa data set, ratio method gives measured W mass as 80435+/-43(stat)+/-26(sys) MeV.