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A search has been performed for weakly interacting neutral light scalar and pseudoscalar particles in a proton-iron beam dump experiment via the Bethe-Heitler process. No positive signal was observed. Limits are derived on the masses of these particles in the framework of the Standard Model and its minimal supersymmetric extension (MSSM) comparing the experimental results with expectations for Bethe-Heitler e+e− and μ+μ− pair production. The Higgs particle of the SU2L×U1 Standard Theory is excluded for masses in the range mH<0.9 MeV at 95% CL. Limits on light Higgs particles of the MSSM and Peccei-Quinn like axions are derived.

Measurements of the Charge Asymmetry of the Dalitz Plot Parameters for Decays AbstractThe charge asymmetry of the g, h, and k Dalitz plot parameters for K ± → π ± π 0 π 0 decays has been measured with 35 GeV/c hadron beams at the 70 GeV IHEP accelerator. The g, h, and k values obtained appear to be identical for K ± decays within the errors quoted. In particular, the charge asymmetry A g = (g + −g − )/(g + + g − ) of the slope g is equal to (0.2 ± 1.9) · 10 −3 .

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The g, h, and k Dalitz plot parameters, which are coefficients in a series expansion of the squared module of the matrix element |M (u, v)| 2 ∝ 1+gu+hu 2 +kv 2 (u, v are invariant variables), have been measured for K ± → π ± π 0 π 0 decays using 35 GeV /c hadron beams at the IHEP (Protvino) accelerator. Dependences of parameters and fit quality on the π 0 π 0 mass cut were investigated. The results point to the important role of π + π − → π 0 π 0 charge exchange scattering near the π 0 π 0 mass threshold. The comparison of our data with previous measurements is presented.