OPERA tau neutrino candidate event 11172035775

It consists of five tracks, one of them exhibiting a kink of 98~mrad after a flight length of 1100~$\mu$m.</p><p>No heavily ionizing track was found pointing at the secondary vertex, as expected in a decay vertex. A $\gamma$-ray was found pointing to primary vertex with an impact parameter of 11~$\mu$m and reconstructed momentum of 1.6~GeV/c. All tracks were followed in the downstream brick and classified as hadrons using their overall track length reconstructed along all the downstream available bricks, the topology at their end-point and the correlation between their momentum and range.

The energy of the neutrino interaction was measured to be $26.5$~GeV/c.</p><p>This event was thus interpreted as a $\nu_{\tau}$ charged-current interaction with the $\tau$ lepton decaying into a single hadron.</p>