ABC effect as a signal of chiral symmetry restoration in hadronic collisions

Abstract

A new nonconventional mechanism for the basic 2π-fusion reaction pn --> d+(ππ)_0 in the energy region T_p = 1.0-1.4 GeV is suggested. The mechanism is aimed at providing a consistent explanation for the comprehensive experimental studies of this reaction in exclusive setting done recently by the WASA-at-COSY Collaboration. The basic assumption of the model proposed is the production of the I(JP) = 0(3+) dibaryon resonance D03 in the pn collision. The interference of two decay channels of this resonance: D_03 --> d + σ --> d + (ππ)_0 and D_03 --> D_12 + π --> d + (ππ)_0 is shown to give a strong near-threshold enhancement in the ππ invariant mass spectrum, which is well known as the ABC effect. The σ-meson parameters found to reproduce the ABC enhancement are in a general agreement with models which predict the chiral symmetry restoration at high excitation energy and/or high density of matter, although they are essentially less than those accepted for the free σ meson. So, this result might be considered as an indication of partial chiral symmetry restoration in dense and excited quark matter.

arXiv comment6 pages, 3 figures

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Cited by in corpus (21)

• On the History of Dibaryons and their Final Observation
• Three-body calculation of the Delta-Delta dibaryon candidate D(03) at 2.37 GeV
• Measurement of the $pn\to pp{\pi }^0{\pi }^{-}$ Reaction in Search for the Recently Observed Resonance Structure in $d{\pi }^0{\pi }^0$ and $d{\pi }^{+}{\pi }^{-}$ systems
• Measurement of the $np\to np{\pi }^0{\pi }^0$ Reaction in Search for the Recently Observed $d^{\ast }(2380)$ Resonance
• Decay width of $d^{\ast }(2380)\to NN\pi \pi$ processes
• Hidden dibaryons in one- and two-pion production in NN collisions
• The $d^{\ast }(2380)$ in neutron stars - a new degree of freedom?
• Decay width of $d^{\ast }(2380)\to NN\pi$ process in a chiral constituent quark model
• Dibaryons: Molecular versus Compact Hexaquarks
• Manifestation of the $P$-wave diproton resonance in single-pion production in $pp$ collisions
• Dibaryon resonances and short-range $NN$ interaction
• To the nature of nuclear force
• An Isotensor Dibaryon in the $pp\to pp{\pi }^{+}{\pi }^{-}$ Reaction?
• On the form factors of $d^{\ast }(2380)$
• On the charge distribution of $d^{\ast }(2380)$
• Photo-absorption on deuteron contributed by d^*(2380) resonance
• Electromagnetic properties of the $d^{\ast }(2380)$ hexaquark
• $P$-wave dibaryon resonances in $pp$ elastic scattering and near-threshold pion production
• Resonance-like coherent production of a pion pair in the reaction $pd\to pd\pi \pi$ in the GeV region
• Isospin symmetry breaking in double-pion production in the region of $d^{\ast }(2380)$ and the scalar $\sigma$ meson
• Possible dibaryon production at $\bar{\mathrm{P}}$anda with a Lagrangian approach