The Experimental Status of the Standard Electroweak Model at the End of the LEP-SLC Era

Abstract

A method is proposed to calculate the confidence level for agreement of data with the Standard Model (SM) by combining information from direct and indirect Higgs Boson searches. Good agreement with the SM is found for $m_H \simeq 120$ GeV using the observables most sensitive to $m_H$: $A_l$ and $m_W$. In particular, quantum corrections, as predicted by the SM, are observed with a statistical significance of forty-four standard deviations. However, apparent deviations from the SM of 3.7$\sigma$ and 2.8$\sigma$ are found for the Z$\nu \bar{\nu}$ and right-handed Zb$\bar{{\rm b}}$ couplings respectively. The maximum confidence level for agreement with the SM of the entire data set considered is $\simeq 0.006$ for $m_H \simeq 180$ GeV. The reason why confidence levels about an order of magnitude higher than this have been claimed for global fits to similar data sets is explained.Comment: 47 pages, 8 figures, 24 tables. An in-depth study of statistical issues related to the comparison of precision EW data to the S