The e+e- B Factories, owing to the large cross section for producing tau lepton pairs, are also "tau factories". In particular, the Belle II experiment will offer fantastic possibilities to study tau physics with high precision, in fact since the decays of tau leptons involve neutrinos in the final state their study is very difficult at hadron colliders such as LHC. The tau lepton is the only lepton that can decay into hadrons, thus providing a perfect laboratory to study QCD effects in the 1 GeV energy region. Moreover, the tau lepton is an extremely convenient probe to search for new Physics beyond the Standard Model because of the well-understood mechanisms tha govern its production and decay in electroweak interactions.

Experimental