Speaker
Description
We report a direct determination of the strange-quark fraction in hadronic Z decays using DELPHI open data. A five-flavor ParticleNet representation defines exclusive flavor-enriched and remainder counts, while an independent data/simulation sample constrains the flavor response and its associated uncertainties. A simultaneous fit with freely floating bottom and charm fractions separates the strange contribution from the complementary (u+d) component without imposing (Rd = Rs), allowing the light-flavor composition to be determined directly from the flavor-tagged event yields. The heavy-flavor results agree with established LEP measurements, providing a consistency check on the flavor separation. The analysis demonstrates how modern flavor-tagging techniques can be applied to archival LEP data to revisit the flavor structure of hadronic Z decays and precision studies of light-quark production in QCD. Response calibration, rather than counting statistics, limits the precision.
