arXiv subjects
Publications and source records attributed to A. A. Lednev.
A search for rare decay $η' \rightarrow 4 π^{0}$ has been performed with GAMS-4$π$ Setup. The new upper limit for decay was established $BR(η' \rightarrow 4 π^{0}) < 3.2 \cdot 10^{-4}$ at 90\% confidence level. The $π^{-} p$ charge-exchange reaction at 32.5 GeV/c was used as a source of $1.3\cdot 10^{6}$ $ η'$ mesons. Experiment carried out at the IHEP U-70 accelerator.
The results of mixing angle measurement for $η'$, $η$ mesons generated in charge exchange reactions with $π^{-}$ and $K^{-}$ beams are preseneted. When the $η'$, $η$ mesons are described in nonstrange(NS)--strange(S) quark basis the $π^{-}$ and $K^{-}$ beams allow to study $|η_{q}>$ and $|η_{s}>$ parts of the meson wave function. The cross section ratio at $t'=0$ (GeV/c)$^{2}$ in the $π^{-}$ beam is $R_π(η'/η)= 0.56 \pm 0.04$, results in mixing angle $ϕ_{P} = (36.8 \pm 1.)^{o} $. For $K^{-}$ beam the ratio is $R_{K}(η'/η)= 1.30 \pm 0.16$. It was found that gluonium content in $η'$ is $\sin^{2}ψ_{G}= 0.15 \pm 0.06$. The experiment was carried out with GAMS-4$π$ Setup.
The reaction $π^-p \to ηπ^o n$ has been studied with GAMS-2000 spectrometer in the secondary 38 GeV/c $π^-$-beam of the IHEP U-70 accelerator. Partial wave analysis of the reaction has been performed in the $ηπ^o$ mass range up to 1200 MeV. The $a_0(980)$-meson is seen as a sharp peak in S-wave. The $t$-dependence of $a_0(980)$ production cross section has been studied. Dominant production of the $a_0(980)$ at a small transfer momentum $t$ confirms the hypothesis of Achasov and Shestakov about significant contribution of the $ρ_2$ exchange ($I^GJ^{PC}=1^+2^{--}$) in the mechanism of $a_0(980)$ meson production in $t$-channel of the reaction.