Resonance structure in the γγ and $π^0π^0$ systems in dC interactions

Abstract

Along with $π^0$ and η mesons, a resonance structure in the invariant mass spectrum of two photons at Mγγ = 360 \pm 7 \pm 9 MeV is observed in the reaction d + C \rightarrow γ + γ + X at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are Γ = 64 \pm 18 MeV and $σ_{γγ}$ = 98 \pm 24 μb, respectively. The collected statistics amount to 2339 \pm 340 events of 1.5 \cdot 10^6 triggered interactions of a total number ~ 10^12 of dC-interactions. The results on observation of the resonance in the invariant mass spectra of two $π^0$ mesons are presented: the data obtained in the d + C \rightarrow γ + γ reaction is confirmed by the d + C \rightarrow $π^0$ + $π^0$ reaction: $M_{π^0π^0}$ = 359.2 \pm 1.9 MeV, Γ = 48.9 \pm 4.9 MeV; the ratio of Br(R\rightarrowγγ) / Br(R\rightarrow$π^0π^0$) = (1.8 ÷ 3.7)\cdot10^-3.