Diphoton and dipion productions at the Nuclotron/NICAстатья
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Дата последнего поиска статьи во внешних источниках: 24 октября 2016 г.
Аннотация:Along with π0 and η mesons, a resonance structure in the invariant-mass spectrum of two
photons at Mγγ = 360±7±9MeV is observed in the reaction dC → γ+γ+X at momentum 2.75GeV/c per
nucleon. Estimates of its width and production cross section are Γ =64±18MeV and σγγ =98±24+93−67 µb, respectively. The collected statistics amount to 2339 ± 340 events of 1.5·106 triggered interactions of a total number ∼ 1012 of d + C interactions. This resonance structure is not observed in the γγ channel in ∼ 1011 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±13MeV, Γ =62±37MeV and σ = 273±75 µb. Some results on the observation of the resonance in the invariant-mass spectra of two π0 mesons are presented: the data
obtained in the d + C → γ + γ + X reaction is confirmed by the results for the d + C → π0
+ π0 + X and p + C → π0 + π0 + X reactions; a preliminary estimate of the ratio Br(R → γγ)/Br(R → π0π0) is (1.8-3.7)·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 1-6 GeV/n and the mechanism of its formation.