Exclusive measurement of two-pion production in the dd --> 4Hepipi reaction

Abstract

The results from the first kinematically complete measurement of the dd --> 4Hepipi reaction are reported. The aim was to investigate a long standing puzzle regarding the origin of the peculiar pipi-invariant mass distributions appearing in double pion production in light ion collisions, the so-called ABC effect. The measurements were performed at the incident deuteron energies of 712 MeV and 1029 MeV, with the WASA detector assembly at CELSIUS in Uppsala, Sweden. We report the observation of a characteristic enhancement at low pipi-invariant mass at 712 MeV, the lowest energy yet. At the higher energy, in addition to confirming previous experimental observations, our results reveal a strong angular dependence of the pions in the overall centre of mass system. The results are qualitatively reproduced by a theoretical model, according to which the ABC effect is described as resulting from a kinematical enhancement in the production of the pion pairs from two parallel and independent NN--> dpi sub-processes.

arXiv comment20 pages including 18 figures

References in corpus (10)

• Double-Pionic Fusion of Nuclear Systems and the ABCEffect -- Aproaching a Puzzle by Exclusive and Kinematically Complete Measurements
• Theoretical study of the N N --> N N pi pi reaction
• The WASA Detector Facility at CELSIUS
• Exclusive Measurements of $pd{\to }^{3}He\pi \pi$ : the $ABC$ Effect Revisited
• Gluon saturation effects on J/Psi production in heavy ion collisions
• The role of the Roper resonance in n p --> d (pi pi)
• 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
• Two-pion production in deuteron-deuteron collisions at low energies

Cited by in corpus (12)

• ABC Effect in Basic Double-Pionic Fusion --- Observation of a new resonance?
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• ABC Effect and Resonance Structure in the Double-Pionic Fusion to ${}^3$He
• ABC Resonance Structure in the Double-Pionic Fusion to 4He
• Exclusive Measurements of pp -> dpi+pi0: Double-Pionic Fusion without ABC Effect
• Experimental and theoretical evidences for an intermediate $\sigma$-dressed dibaryon in the NN interaction
• Six-quark structure of $d^{\ast }(2380)$ in chiral constituent quark model
• Properties of single cluster structure of $d^{\ast }(2380)$ in chiral SU(3) quark model
• Isospin effects in the exclusive dp -> 3Heπ+π- reaction
• The opportunity to find ${\bar{d}}^{\ast }(2380)$ in the ${\rm Y}(nS)$ decay
• Phenomenological study on the decay widths of ${\rm Y}(nS)\to {\bar{d}}^{\ast }(2380)+X$
• The ABC Effect in Double-Pionic Nuclear Fusion and a pn Resonance as its Possible Origin