Dr. Michel Villanueva (Brookhaven National Laboratory)

Tau Leptons at the Intensity Frontier: Challenges, Results and Prospects from Belle II 

As the heaviest lepton, the tau can decay to both hadronic and purely leptonic final states, offering diverse possibilities to search for new physics.  Belle II, operating at the SuperKEKB electron-positron collider, plays a critical role in searches for new physics at the intensity frontier with a dataset projected to be 50 times that of its predecessors. I will cover precision determinations of the tau lepton mass at Belle II and tests of lepton-flavor universality, emphasizing the challenges associated with systematic uncertainties, and searches for lepton flavor violation, where the clean environment of electron-positron collisions, a large data set enabled by distributed computing, and the excellent performance of the detector enhance the sensitivity into unexplored territory. I will summarize the current status, analysis strategies, and near-term milestones, and discuss how Belle II results sharpen the global picture of new-physics scenarios.