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.

6 pages, 3 figures

References in corpus (6)

• 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
• Quark models of dibaryon resonances in nucleon-nucleon scattering
• Delta Delta Excitation in Proton-Proton Induced pi0pi0 Production
• Chiral symmetry and the string description of excited hadrons
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Cited by in corpus (3)

• On the History of Dibaryons and their Final Observation
• Manifestation of the $P$-wave diproton resonance in single-pion production in $pp$ collisions
• Photo-absorption on deuteron contributed by d^*(2380) resonance