New method for non-standard invisible particle searches in tau lepton decays
Motivated by models proposed to explain the Standard Model anomalies, and the unprecedented $τ^{+}τ^{-}$ data to be collected by the Belle~II experiment during the next years, we study the kinematics of tau pair decays and propose a new method to search for lepton flavor violating processes in tau lepton decays to invisible beyond Standard Model particles, such as $τ\to \ell α$, where $\ell$ is either an electron or a muon, and $α$ is a massive particle that escapes undetected. The new method improves by one order of magnitude the expected upper limit on the $τ\to \ell α$ production in 3x1 prong tau decays and establishes the possibility of performing this search in 1x1 prong tau decays which has not been previously considered.
hep-ph↗