Resonance Structure in the $\gamma \gamma$ Invariant Mass Spectrum in $p$C- and $d$C-Interactions

Abstract

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 $dC\to \gamma +\gamma +X$ at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are $\Gamma =63.7\pm 17.8$ MeV and ${\sigma }_{\gamma \gamma }=98\pm 24_{-67}^{+93}\mu \mathrm{b}$, 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 $p$C collisions at the beam momentum 5.5 GeV/c. Possible mechanisms of this ABC-like effect are discussed.

References in corpus (19)

• The Cosmological Parameters 2006
• Big-Bang nucleosynthesis (Particle Data Group mini-review)
• Mass and width of the lowest resonance in QCD
• Dielectron production in 12C+12C collisions at 2 AGeV with HADES
• Dilepton production and off-shell transport dynamics at SIS energies
• Wavelets and their use
• Study of dielectron production in C+C collisions at 1 AGeV
• Di-Electron Bremsstrahlung in Intermediate-Energy pn and Dp Collisions
• Description of intermediate- and short-range NN nuclear force within a covariant effective field theory
• Level crossing of particle-hole and mesonic modes in eta mesic nuclei
• The properties of the three-nucleon system with the dressed-bag model for nn interaction. I: New scalar three-body force
• Search for NN-decoupled dibaryons using the process $pp\to \gamma \gamma X$ below the pion production threshold
• Study of the ABC Enhancement in the d d -> alpha X reaction
• Structure in two_pion production in the d d -> alpha X reaction
• An explanation of the ABC enhancement in the dd -> alpha X reaction at intermediate energies
• Single- and Double-Pion Production in Nucleon Collisions on the Nucleon and on Nuclei -- the ABC Effect and its Possible Origin in a Dibaryonic Resonance
• The properties of the three-nucleon system with the dressed-bag model for $NN$ interaction. II: Coulomb and CSB effects
• On possible existence of the dibaryon resonance $d_1^{\ast }$ and its role in the $np\gamma$ and $pd\gamma$ processes below the pion threshold
• Observation of New Resonance Structure in the Invariant Mass Spectrum of Two gamma-Quanta in dC-Interactions at Momentum 2.75 GeV/c per Nucleon

Cited by in corpus (8)

• On the History of Dibaryons and their Final Observation
• Experimental and theoretical evidences for an intermediate $\sigma$-dressed dibaryon in the NN interaction
• On the question of quark confinement in the Abelian U(1) QED gauge interaction
• Isospin symmetry breaking in double-pion production in the region of $d^{\ast }(2380)$ and the scalar $\sigma$ meson
• QED meson description of the anomalous particles at ~17 and ~38 MeV
• Resonance structure in the γγ and ${\pi }^0{\pi }^0$ systems in dC interactions
• Compact $N$-quark Hadron Mass Dependence on $N^4$: A Classical Field Picture
• The light quark coupling of the E(38) boson candidate