Heavy Flavour Electroweak Physics Review

TL;DR

This review summarizes precise measurements of Z boson decay widths and asymmetries into b and c quarks from LEP and SLD, testing the electroweak sector of the Standard Model and highlighting a notable discrepancy in the electroweak mixing angle.

Contribution

It provides a comprehensive overview of electroweak measurements related to heavy flavor quarks, emphasizing the significance of the observed discrepancy in the mixing angle from different methods.

Findings

Precise determination of electroweak coupling constants

Observation of a three-standard-deviation discrepancy in the mixing angle

Detailed discussion of b quark asymmetry measurements

Abstract

The four LEP experiments and the SLD detector have measured the Z partial widths for Z decays into b and c quarks and the corresponding forward-backward asymmetries at centre-of-mass energies close to the Z boson mass. The results yield a very precise determination of the effective vector and axial-vector coupling constants and of the underlying electroweak mixing angle sin(theta[eff,lep]), probing the Standard Model prediction for the electroweak radiative corrections. Of special interest is hereby a difference at the level of three standard deviations in the mixing angle results from lepton production and those obtained from the forward-backward asymmetry in b quark production. The b quark asymmetry measurements, some of which are still in the process of being finalised, are therefore discussed in detail.