Observation of the ABC effect in the reaction n+p → d+(mm)0 with A 1.88 GeV/c neutron beam

Plouin, F.; Duflo, J.; Goldzahl, L.; Bizard, G.; Bonthonneau, F.; Cottereau, M.; Laville, J.L.; Brun, C. Le; Lefebvres, F.; Malherbe, Johan; Régimbart, R.

doi:10.1016/0375-9474(78)90331-7

Cited by 50 publications

(30 citation statements)

References 19 publications

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“…This experiment is somewhat similar to the one of Plouin et al [9], but at lower energies ( T n = 795 MeV in [14] vs 1160 MeV in [9] ). Therefore, the analysis is simpler since, once the π 0 peaks are subtracted, only the double pion production mechanism is present.…”

Section: Introductionsupporting

confidence: 85%

The role of the Roper resonance in np→d(ππ)0

Alvarez‐Ruso

1999

Physics Letters B

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In this work, a model for the np → d(ππ) 0 reaction is developed. It is shown that the structure of the deuteron momentum spectra for a neutron beam momentum of 1.46 GeV can be explained as a consequence of the interplay of two mechanisms involving the excitation of the N * (1440) resonance and its subsequent decay into N (ππ) T =0 S−wave and ∆π respectively. The relevance of the present analysis for the study of the Roper excitation and decay properties, as well as for the interpretation of other two-pion production experiments is discussed.

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Section: Introductionsupporting

confidence: 85%

The role of the Roper resonance in np→d(ππ)0

Alvarez‐Ruso

1999

Physics Letters B

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“…Subsequent measurements showed that this enhancement also persists in the fusion reactions to d and 4 He [18][19][20][21][22][23][24][25][26][27][28], if the produced pion pair is of isoscalar nature. Since there was no plausible explanation for this effect, it got named after the initials of the authors of the first publication on that issue.…”

Section: Abc Effectmentioning

confidence: 99%

Examination of the nature of the ABC effect

2017

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Recently it has been shown by exclusive and kinematically complete experiments that the appearance of a narrow resonance structure in double-pionic fusion reactions is strictly correlated with the appearance of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the ππ-invariant mass spectrum. Whereas the resonance structure got its explanation by the d * (2380) dibaryonic resonance, a satisfactory explanation for the ABC effect is still pending. In this paper we discuss possible explanations of the ABC effect and their consequences for the internal structure of the d * dibaryon. To this end we examine and review a variety of proposed explanations for the ABC effect, add a new hypothesis and confront all of them with the experimental results for the np → dπ 0 π 0 and np → npπ 0 π 0 reactions, which are the most challenging ones for this topic.

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“…Its explanation has been a puzzle since then. In subsequent bubble-chamber [2,3] and single-arm magnetic spectrometer measurements [4][5][6][7][8][9][10][11][12] this enhancement was observed also in double-pionic fusion reactions leading to d, 3He, and 4He, if an isoscalar pion pair was produced. However, such an enhancement was not observed in fusion reactions leading to deuteron and triton, if an isovector pion pair was produced.…”

Section: Introductionmentioning

confidence: 99%

ABC effect and resonance structure in the double-pionic fusion toHe3

Adlarson¹,

Augustyniak²,

Bardan³

et al. 2015

Phys. Rev. C

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Exclusive and kinematically complete measurements of the double pionic fusion to 3He have been performed in the energy region of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the 7T7r-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY (the cooler synchrotron at Forschungszentrum Jiilich). Similar to the observations in the basic pn -* d n 07t° reaction and in the dd 4 He n ajr0 reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. Differential cross sections are well described by the hypothesis of d* resonance formation during the reaction process in addition to the conventional /-channel AA mechanism. The deduced d* resonance width can be understood from collision broadening due to Fermi motion of the nucleons in initial and final nuclei.

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Observation of the ABC effect in the reaction n+p → d+(mm)0 with A 1.88 GeV/c neutron beam

Cited by 50 publications

References 19 publications

The role of the Roper resonance in np→d(ππ)0

The role of the Roper resonance in np→d(ππ)0

Examination of the nature of the ABC effect

ABC effect and resonance structure in the double-pionic fusion toHe3

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