Evidence of a dibaryon spectrum in coherent ${\pi }^0{\pi }^{0}d$ photoproduction at forward deuteron angles

Abstract

The coherent reaction, $\gamma d\to {\pi }^0{\pi }^{0}d$ was studied with the BGOOD experiment at ELSA from threshold to a centre-of-mass energy of 2850\,MeV. A full kinematic reconstruction was made, with final state deuterons identified in the forward spectrometer and ${\pi }^0$ decays in the central BGO Rugby Ball. The strength of the differential cross section exceeds what can be described by models of coherent photoproduction and instead supports the three isoscalar dibaryon candidates reported by the ELPH collaboration at 2.38, 2.47 and 2.63\,GeV/c${}^2$. A low mass enhancement in the ${\pi }^0{\pi }^0$ invariant mass is also observed at the $d^{\ast }(2380)$ centre-of-mass energy which is consistent with the ABC effect. At higher centre-of-mass energies, a narrow peak in the ${\pi }^{0}d$ invariant mass at 2114\,MeV/c${}^2$ with a width of 20\,MeV/c${}^2$ supports a sequential two-dibaryon decay mechanism.

arXiv comment8 pages, 10 figures. Additional references (recommended by colleagues) added since the first revision

References in corpus (25)

• ABC Effect in Basic Double-Pionic Fusion --- Observation of a new resonance?
• Double-Pionic Fusion of Nuclear Systems and the ABCEffect -- Aproaching a Puzzle by Exclusive and Kinematically Complete Measurements
• Evidence for a New Resonance from Polarized Neutron-Proton Scattering
• On the History of Dibaryons and their Final Observation
• Isospin Decomposition of the Basic Double-Pionic Fusion in the Region of the ABC Effect
• Theoretical study of the N N --> N N pi pi reaction
• Three-body calculation of the Delta-Delta dibaryon candidate D(03) at 2.37 GeV
• Three-body model calculations of Nucleon-Delta and Delta-Delta dibaryon resonances
• Double pion photoproduction on nucleon and deuteron
• Measurement of the $np\to np{\pi }^0{\pi }^0$ Reaction in Search for the Recently Observed $d^{\ast }(2380)$ Resonance
• Study of the gamma p --> pi0 pi0 p reaction with the Crystal Ball/TAPS at the Mainz
• The role of the Roper resonance in n p --> d (pi pi)
• First measurement of coherent double neutral-pion photoproduction on the deuteron at incident energies below 0.9 GeV
• The $d^{\ast }(2380)$ in neutron stars - a new degree of freedom?
• Non-strange Dibaryon Resonances Observed in the $\gamma d\to {\pi }^0{\pi }^{0}d$ Reaction
• Triangle singularity mechanism for the $pp\to {\pi }^{+}d$ fusion reaction
• ABC Resonance Structure in the Double-Pionic Fusion to 4He
• The BGOOD experimental setup at ELSA
• Dibaryons: Molecular versus Compact Hexaquarks
• $K^{+}\Lambda$ photoproduction at forward angles and low momentum transfer
• Signatures of the $d^{\ast }(2380)$ hexaquark in d($\gamma$,$p\vec{n}$)
• Coherent pi0-pi0 photoproduction on lightest nuclei
• A new possibility for light-quark Dark Matter
• Photo-absorption on deuteron contributed by d^*(2380) resonance
• Comment on "Sequential Single-Pion Production Explaining the Dibaryon "$d^{\ast }(2380)$" Peak"

Cited by in corpus (3)

• Reply to "Comment on Sequential Single-pion Production Explaining the dibaryon $d^{\ast }(2380)$ peak''
• Sequential single pion production explaining the dibaryon "$d^{\ast }(2380)$" peak
• On Sequential Single-Pion Production in Double-Pionic Fusion