Latest results in the τ physics and the dark sector from the Belle II experiment

Belle II has a leading role in the tau sector and dark sector due to its large tau sample and unique sensitivity for a broad class of models postulating the existence of dark matter particles with masses in the MeV-GeV range. We present recent world-leading results from the Belle II collaboration for: lepton universality test through the leptonic tau decay; search for a lepton flavor violating tau decay; production of an X state decaying in two muons, interpretable both as a Z(') boson or a muonphilic dark scalar; search for a long-lived scalar or axion-like particle produced in decays of B-mesons.