The paper "Measurement of \(B^+ \to \tau^+ \nu_\tau\) branching fraction with a hadronic tagging method at Belle II" in which Michele Aversano has contributed as the main author, was published in Physical Review D.

In this thesis work, we measure the branching fraction of the decay \(B^+ \to \tau^+ \nu_\tau\) using \(e^+e^−\) collision data collected by the Belle II experiment at the SuperKEKB collider. The result is compared with predictions from the Standard Model and with previous experiments, demonstrating a comparable statistical uncertainty despite using a smaller dataset. Candidate events are reconstructed using a hadronic tagging method based on multivariate analysis, which effectively suppresses background noise. The signal events are searched through several \(\tau\) decay modes (to electron, muon, pion, and rho),selected with optimized criteria including machine learning classifiers. The branching fraction is determined using a multidimensional maximum-likelihood fit, with simulation models calibrated to match experimental data and account for systematic uncertainties. As the main analyst, he developed the event selection, optimized the machine learning models, and performed the final fit to extract the branching fraction.

Paper information:
ADACHI, I., et al. "Measurement of \(B^+ \to \tau^+ \nu_\tau\) branching fraction with a hadronic tagging method at Belle II"
[Phys. Rev. D, 112, 072002, 2025. DOI:https://doi.org/10.1103/PhysRevD.112.072002]