Observation of charmed F+ meson produced by neutrino interaction in emulsion

Any event representing the production and decay of the charmed F+ meson has been identified by means of a 3‐constraint fit to the decay hypothesis F+→π+π+π−π0, in which both γ‐rays from the π0 converted. The event was produced by a charged current νμ interaction in an emulsion stack located inside the Fermilab 15‐foot bubble chamber. The F+ traveled 50 μm, corresponding to a proper time of 1.4×10−13 seconds, before decaying in flight. Its mass was determined to be 2017±25 MeV.