%0 Journal Article
%A Mękała, Krzysztof
%A Jeans, Daniel
%A Reuter, Jürgen
%A Tian, Junping
%A Żarnecki, Aleksander Filip
%T Determination of the first-generation quark couplings at the Z-pole
%J Journal of high energy physics
%V 11
%N 11
%@ 1126-6708
%C Heidelberg
%I Springer
%M PUBDB-2025-05134
%M arXiv:2504.11365
%M DESY-25-063
%P 050
%D 2025
%Z cc-by, JHEP11(2025)050. 22 pages, 8 figures
%X 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, which are currently constrained from LEP data to a few percent, could reveal potential discrepancies from theoretical predictions. Future e<sup>+</sup>e<sup>−</sup> colliders running at the Z-pole would be an excellent tool to improve these constraints. In this paper, we present a method to extract the values of the Z couplings to light quarks based on up- and down-quarks’ different contributions to radiative and non-radiative Z boson decays. We show that systematic uncertainty in the heavy-flavour tagging performance is the key factor in the analysis, and that reducing it to the sub-permille level is crucial to fully profit from the high luminosity of future e<sup>+</sup>e<sup>−</sup> machines. The measurement could improve the LEP results by at least an order of magnitude.
%K Electroweak Precision Physics (autogen)
%K Flavour Symmetries (autogen)
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1007/JHEP11(2025)050
%U https://bib-pubdb1.desy.de/record/641723