Latest results of the OPERA experiment on nu-tau appearance in the CNGS neutrino beam

OPERA is a long-baseline experiment designed to search for$\nu_{\mu}\to\nu_{\tau}$ oscillations in appearance mode. It was based at theINFN Gran Sasso laboratory (LNGS) and took data from 2008 to 2012 with the CNGSneutrino beam from CERN. After the discovery of $\nu_\tau$ appearance in 2015,with $5.1\sigma$ significance, the criteria to select $\nu_\tau$ candidateshave been extended and a multivariate approach has been used for eventsidentification. In this way the statistical uncertainty in the measurement ofthe oscillation parameters and of $\nu_\tau$ properties has been improved.Results are reported.