Erlangen 2026 – scientific programme
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T: Fachverband Teilchenphysik
T 72: Flavour Physics IV
T 72.3: Talk
Thursday, March 19, 2026, 16:45–17:00, KH 01.011
Transformer-based classification of Bs0→τ+ τ− decays in Z → bb events at the FCC-ee — •Alejandro Quiroga Trivino1, Jan Kieseler1, Markus Klute1, Joscha Knolle1, Anuar Sifuentes Name1, Samuel Wyrowski1, and Xunwu Zuo2 — 1Institute for Experimental Particle Physics (ETP), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany — 2Ecole polytechnique federale de Lausanne (EPFL), Lausanne, Switzerland
Experimental indications of potential deviations from lepton flavor universality have intensified interest in rare B meson decays involving tau leptons. Among these, the decay Bs0 → τ+ τ− remains largely unexplored experimentally due to its challenging final state and the limited sensitivity of current detectors. The high-statistics and low-background environment of electron-positron collisions at the Z pole that will be provided by the FCC-ee creates a unique opportunity to study this process with unprecedented precision. Leveraging these conditions, advanced machine-learning techniques can be brought to bear to enhance the separation between signal candidates and the overwhelming Z → b b background. In this contribution, the application of a transformer model to separate between Z→ b b events with and without a Bs0 → τ+ τ− decay is discussed. The usage of different sets of input features, relying either on reconstructed hadronic tau lepton candidates or on tracks and neutral particles, are compared. The achieved background rejection paths the way towards the observation of this rare standard model process.
Keywords: B physics; future circular collider; tau physics; machine learning