Theory of Z boson decays

TL;DR

This paper compares precise Z boson decay data from LEP-I and SLC with Standard Model predictions, emphasizing one-loop electroweak corrections and discussing potential signs of new physics.

Contribution

It provides a detailed analysis of Z decay data within the Standard Model, focusing on one-loop electroweak corrections and the implications for new physics.

Findings

Agreement between data and Standard Model predictions within uncertainties

Electroweak loop corrections are significant for precision tests

Potential deviations could indicate new physics phenomena

Abstract

The precision data on Z boson decays from LEP-I and SLC colliders are compared with the predictions based on the Minimal Standard Theory. The Born approximation of the theory is based on three most accurately known observables: G_mu -- the four fermion coupling constant of muon decay, m_Z -- the mass of the Z boson, and alpha(m_Z) -- the value of the running fine structure constant at the scale of m_Z. The electroweak loop corrections are expressed, in addition, in terms of the masses of higgs, m_H, of the top and bottom quarks, m_t and m_b, and of the strong interaction constant alpha_s(m_Z). The main emphasis of the review is focused on the one-electroweak-loop approximation. Two electroweak loops have been calculated in the literature only partly. Possible manifestations of new physics are briefly discussed.