Search For Heavy Neutral Spinless Particles Using E+E--]E+E- And E+E--] Gamma-Gamma Reactions In The Cm Energy-Range Between 54 And 64 Gev

Heavy neutral spinless particles are searched for using e+ e- collision data of CM energies between 54 and 64 GeV, collected with the VENUS detector at TRISTAN. The existence of such a particle might explain the anomalous e+e- --> l+l-gammagamma reaction recently reported by a LEP experiment. Negative results lead to constraints on the partial decay width of such particles to electrons: in narrow resonance cases, GAMMA(ee) < 1 MeV from Bhabha scattering data and GAMMA(ee)B(gammagamma) < 3 keV from gammagamma production data at the 95% CL for masses around 59 GeV/c2.