Observation of the four-pion decay mode of the D(1285) meson in π±p reactions at 16 GeV/c

Abstract A narrow peak is observed at 1283 ± 6 MeV in the (π + π + π − π − ) mass distribution in the reactions π ± p → π ± p(4π) 0 at 16 GeV/ c . This is interpreted as evidence for a four-pion decay mode of the D-meson. It is shown that this enhancement is mainly ϱππ. The cross section for π ± p → π ± pD 0 , with D 0 → π + π + π − π − is 16 ± 5 μb and 6.0 ± 1.5 μb for incident π + and π − , respectively. An upper limit of 1.8 is established for the ratio of (ηπ + π − ) to (π + π + π − π − ) decay modes of the D-meson.