Search for lepton-flavor-violating \(\tau\) decays into a lepton and a vector meson using the full Belle data sample

Charged-lepton-flavor-violation is predicted in several new physics scenarios. We update the analysis of \(\tau\) lepton decays into a light charged lepton (\(\ell\) = \(e^{\pm}\) or \(\mu^{\pm}\)) and a vector meson (\(V^0\) = \(\rho^0\), \(\phi\), \(\omega\), \(K^{\ast0}\), or \(\overline{K}{}^{\ast0}\)) using 980 fb\(^{-1}\) of data collected with the Belle detector at the KEKB collider. No significant excess of such signal events is observed, and thus 90% credibility level upper limits are set on the \(\tau \rightarrow \ell V^0\) branching fractions in the range of (1.7--\(4.3) \times 10^{-8}\). These limits are improved by 30% on average from the previous results.