Diphoton and dipion productions at the Nuclotron/NICA
Abraamyan
Kh.U.
Dubna, JINR
CANDLE, Yerevan
Anisimov
A.B.
Dubna, JINR
Baznat
M.I.
IAP, Chisinau
Gudima
K.K.
IAP, Chisinau
Kozhin
M.A.
Dubna, JINR
Kukulin
V.I.
SINP, Moscow
Tubingen U.
Nazarenko
M.A.
Moscow RAS, IRE
Reznikov
S.G.
Dubna, JINR
Sorin
A.S.
Dubna, JINR
Dubna, JINR
2016
Along with $ \pi^{0}$ and $ \eta$ mesons, a resonance structure in the invariant-mass spectrum of two photons at $ M_{\gamma\gamma} = 360 \pm 7 \pm 9$ MeV is observed in the reaction $ d C \rightarrow \gamma + \gamma +X$ at momentum 2.75GeV/c per nucleon. Estimates of its width and production cross section are $ \Gamma = 64 \pm 18$ MeV and $ \sigma_{\gamma\gamma} = 98 \pm 24^{+93-67}$ μb, respectively. The collected statistics amount to $ 2339 \pm 340$ events of $ 1.5\cdot 10^{6}$ triggered interactions of a total number $ \sim 10^{12}$ of $ d+C$ interactions. This resonance structure is not observed in the $ \gamma$ $ \gamma$ channel in $ \sim 10^{11} p+ C$ collisions at the beam momentum 5.5GeV/c . The result obtained in the reaction $ d+ C$ is confirmed by the second experiment carried out on the deuteron beam at momentum 3.83GeV/c per nucleon with a copper target: $ M = 382 \pm 13$ MeV, $ \Gamma = 62 \pm 37$ MeV and $ \sigma = 273 \pm 75$ μb. Some results on the observation of the resonance in the invariant-mass spectra of two $ \pi^{0}$ mesons are presented: the data obtained in the $ d+C\rightarrow \gamma+\gamma + X$ reaction is confirmed by the results for the $ d+C\rightarrow \pi^{0} +\pi^{0} + X$ and $ p+C\rightarrow \pi^{0} +\pi^{0} + X$ reactions, a preliminary estimate of the ratio $ Br(R\rightarrow\gamma\gamma)/Br (R\rightarrow\pi^{0}\pi^{0})$ is $ (1.8-3.7)\cdot 10^{-3}$ . Further studies of this resonance is assumed at the Nuclotron/NICA at higher setup acceptance, which will allow to elucidate the nature of this resonance by determination of the differential cross sections at different beam energies in the range 1-6GeV/n and the mechanism of its formation.
CORE