The W-Boson Mass and Precision Tests of the Standard Model

Abstract

We have examined the electroweak radiative corrections in the LEP precision data in view of the new measurements of $M_W$ and $m_t$ as well as the recent progress in the higher order radiative corrections. From the minimal $χ^2$-fit to the experimental Z-decay parameters (with the aid of a modified ZFITTER program), we predict that $M_W=80.29(4)(2)$ GeV where the first error is due to the uncertainty in the fitted $m_t$ for a fixed $m_H$ and the second error comes from the $m_H$ in the range of $60-1000$ GeV, which is to be compared with the current world average $M_W=80.23(18)$ GeV. The current world average value of $M_W$ and the 1994 LEP data definitely favor nonvanishing electroweak radiative corrections and are consistent with a heavy $m_t$ as measured by the recent CDF report but with a heavy Higgs scalar of about 400 GeV within the context of the minimal standard model. The sensitivity of and the errors in the best fit solutions due to the uncertainties in the gluonic coupling $α_s(M_Z)$ and $α(M_Z)$ are also studied carefully. In addition we discuss how the future precision measurements of $M_W$ can provide a decisive test for the standard model with radiative corrections and give a profound implication for the measurement of t-quark and Higgs masses.