Evidence for a resonant behaviour in e+e− annihilation into hadrons, around 1820 MeV, at adone

Multihadron production has been measured at the Adone e+e− storage ring in the c.m. energy region 1600 ÷ 1900 MeV. A resonant behaviour is observed, centered at 1819 ± 5 (±2) MeV, with a width of 24 ± 5 (±4) MeV. This effect is observed only in the events with 3 or 4 charged particles together with photons, but not in those without photons.