Observation of an ABC effect in proton-proton collisions

Abstract

The cross section for inclusive multipion production in the pp->ppX reaction was measured at COSY-ANKE at four beam energies, 0.8, 1.1, 1.4, and 2.0 GeV, for low excitation energy in the final pp system, such that the diproton quasi-particle is in the 1S0 state. At the three higher energies the missing mass Mx spectra show a strong enhancement at low Mx, corresponding to an ABC effect that moves steadily to larger values as the energy is increased. Despite the missing-mass structure looking very different at 0.8 GeV, the variation with Mx and beam energy are consistent with two-pion production being mediated through the excitation of two Delta(1232) isobars, coupled to S-- and D-- states of the initial pp system.

4 pages, 3 figures

References in corpus (9)

• The Cosmological Parameters 2006
• Big-Bang nucleosynthesis (Particle Data Group mini-review)
• Double-Pionic Fusion of Nuclear Systems and the ABCEffect -- Aproaching a Puzzle by Exclusive and Kinematically Complete Measurements
• Nucleon-nucleon elastic scattering to 3 GeV
• Two-Pion Production in Proton-Proton Collisions with Polarized Beam
• Production of the 1S0 diproton in the pp -> pp pi0 reaction at 0.8 GeV
• Study of the ABC Enhancement in the d d -> alpha X reaction
• Energy dependence of forward 1S0 diproton production in the pp -> pp pi0 reaction
• The pp -> pp pi pi pi reaction channels in the threshold region

Cited by in corpus (10)

• ABC Effect in Basic Double-Pionic Fusion --- Observation of a new resonance?
• Phenomenological analysis of the double pion production in nucleon-nucleon collisions up to 2.2 GeV
• Hidden dibaryons in one- and two-pion production in NN collisions
• Stability of hexaquarks in the string limit of confinement
• Delta Delta Excitation in Proton-Proton Induced pi0pi0 Production
• Study of the quasi-free $np\to np{\pi }^{+}{\pi }^{-}$ reaction with a deuterium beam at 1.25 GeV/nucleon
• π^0 π^0 Production in Proton-Proton Collisions at Tp=1.4 GeV
• Coupled channels calculation of a pion-Lambda-nucleon quasibound state
• Resonance-like coherent production of a pion pair in the reaction $pd\to pd\pi \pi$ in the GeV region
• The ABC Effect in Double-Pionic Nuclear Fusion and a pn Resonance as its Possible Origin