PRECISE MEASUREMENT OF LIGHT-QUARK ELECTROWEAK COUPLINGS AT FUTURE COLLIDERS

Electroweak Precision Measurements are stringent tests of the Standard Model and sensitive probes to new physics. Accurate studies of the Z-boson couplings to the first-generation quarks could reveal potential discrepancies between the fundamental theory and experimental data. Future lepton colliders offering high statistics of Z bosons would be an excellent tool to perform such a measurement based on a comparison of radiative and non-radiative hadronic decays of the Z boson. Due to the difference in quark charge, the relative contribution of the events with final-state radiation (FSR) directly reflects the ratio of up- and down-type quark decays. Such an analysis requires a proper distinction between photons coming from different sources, including initial-state radiation (ISR), FSR, parton showers, and hadronisation. In our paper, we will show how to extract the values of the Z couplings to quarks and present preliminary results of the analysis for ILC.