M. A. Kozhin

A Resonance structure in the gamma gamma invariant mass spectrum in pC- and dC-interactions

Along with {pi}{sup 0} and {eta} mesons, a resonance structure in the invariant mass spectrum of two photons at M{sub {gamma}}{sub {gamma}}=360{+-}7{+-}9 MeV is observed in the reaction dC{yields}{gamma}+{gamma}+X at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are {gamma}=63.7{+-}17.8 MeV and {sigma}{sub {gamma}}{sub {gamma}}=98{+-}24{sub -67}{sup +93} {mu}b, respectively. The collected statistics amount to 2339{+-}340 events of 1.5x10{sup 6} triggered interactions of a total number {approx}10{sup 12} of dC interactions. This resonance structure is not observed in pC collisions at the beam momentum 5.5 GeV/c. Possible mechanisms of this ABC-like effect are discussed.

Resonance structure in theγγinvariant mass spectrum inpC anddC interactions

Along with {pi}{sup 0} and {eta} mesons, a resonance structure in the invariant mass spectrum of two photons at M{sub {gamma}}{sub {gamma}}=360{+-}7{+-}9 MeV is observed in the reaction dC{yields}{gamma}+{gamma}+X at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are {gamma}=63.7{+-}17.8 MeV and {sigma}{sub {gamma}}{sub {gamma}}=98{+-}24{sub -67}{sup +93} {mu}b, respectively. The collected statistics amount to 2339{+-}340 events of 1.5x10{sup 6} triggered interactions of a total number {approx}10{sup 12} of dC interactions. This resonance structure is not observed in pC collisions at the beam momentum 5.5 GeV/c. Possible mechanisms of this ABC-like effect are discussed.

Inclusive neutral pion production at forward angles at 4.5 GeV/c per nucleon in α+C→π0+x and α+Cu→π0+x reactions

Abstract Distributions for transverse momentum P⊥ and cumulative number X of inclusive neutral pions are measured with a lead glass calorimeter in α+C→π0+x and α+Cu→π0+x reactions at 4.5 GeV/cper nucleon. The target-mass dependence for π0 production is presented.

Resonance structure in the {gamma}{gamma} invariant mass spectrum in pC, dC, and dCu interactions

Along with π0 and η mesons, a resonance structure in the invariant mass spectrum of two photons atMγγ = 360 ± 7 ± 9 MeV is observed in dC interactions at momentum 2.75 GeV/c per nucleon. This resonance structure is not observed in pC collisions at the beam momentum 5.5 GeV/c. The result obtained in the reaction dC is confirmed by the second experiment carried out on the deuteron beam at momentum 3.83 GeV/c per nucleon with a copper target. Some other checks of the observed effect are presented.Along with

Resonance structure in the {\gamma}{\gamma} and

\pi^0

\pi^0\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 2.75 GeV/c per nucleon. Estimates of its width and production cross section are {\Gamma} = 64 \pm 18 MeV and

systems in dC interactions

\sigma_{\gamma\gamma}

Resonance structure in the γγ invariant mass spectrum in pC- and dC-interactions

= 98 \pm 24 {\mu}b, 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

Resonance structure in the γγ invariant mass spectrum in pC, dC, and dCu interactions

\pi^0

Inclusive neutral-pion production in dC and dCu interactions at a momentum of 4.5 GeV/. per nucleon

mesons are presented: the data obtained in the d + C \rightarrow {\gamma} + {\gamma} reaction is confirmed by the d + C \rightarrow