ΔΔ excitation in proton–proton induced <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:msup><mml:mi>π</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:msup><mml:mi>π</mml:mi><mml:mn>0</mml:mn></mml:msup></mml:math> production

Skorodko, T.; Bashkanov, M.; Bogoslawsky, D.; Calén, H.; Clement, H.; Doroshkevich, E.; Demiroers, L.; Ekström, C.; Fransson, K.; Gustafsson, L.; Höistad, B.; Ivanov, G.; Jacewicz, M.; Jiganov, E.; Johansson, T.; Khakimova, O.; Keleta, S.; Koch, I.; Kren, F.; Kullander, S.; Kupść, A.; Marciniewski, P.; Meier, R.; Morosov, B.; Pauly, C.; Petrén, H.; Petukhov, Y.; Povtorejko, A.; Ruber, Roger; Schönning, K.; Scobel, W.; Shwartz, B.; Steṕaniak, J.; Thörngren-Engblom, P.; Tikhomirov, V.; Wagner, G. J.; Wolke, M.; Yamamoto, A.; Zabierowski, J.; Złomańczuk, J.

doi:10.1016/j.physletb.2010.11.030

Cited by 40 publications

(54 citation statements)

References 62 publications

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“…On the contrary the basic isovector fusion process pp → dπ + π 0 exhibits neither an ABC effect nor a narrow resonance structure [14,15] in this particular energy region -in agreement with the observations in all other two-pion channels of pp initiated reactions [16][17][18][19][20][21][22][23][24][25][26][27], i.e. of isovector reactions.…”

Section: Introductionsupporting

confidence: 80%

“…This experimental finding strongly contravenes conventional calculations based on the mutual excitation of the two colliding nucleons to their ∆(1232) state by t-channel meson exchange, which rather predict a gentle two-hump structure relative to phase space (dotted lines in Fig. 1) [12,22,31]. Such conventional calculations give a good account for the data for pp initiated two-pion production [15,22,26].…”

Section: Discussion Of Resultsmentioning

confidence: 68%

“…1) [12,22,31]. Such conventional calculations give a good account for the data for pp initiated two-pion production [15,22,26]. Hence it comes as a surprise that they obviously do not work for pn initiated two-pion production -in particular fusion processes.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

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ABC Effect in Double-Pionic Fusion – a New Resonance?

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Bashkanov

Clement

et al. 2012

EPJ Web of Conferences

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Abstract. The ABC effect, an intriguing low-mass enhancement in the ππ invariant mass spectrum -known since more than 50 years from inclusive measurements of double-pionic fusion reactions -is reexamined. To this end exclusive and kinematically complete high-statistics experiments of the fusion reactions to d, 3 He and 4 He have been carried out with WASA at COSY. These measurements cover the full energy region, where the ABC effect has been observed previously. They also complement the systematic measurements of nucleon-nucleon induced two-pion production. An isospin decomposition of all three basic double-pionic fusion reactions leading to the deuteron uniquely shows that solely the isoscalar reaction part exhibits the ABC effect tightly correlated with a narrow resonance structure in the total cross section. The peak energy of the resonance structure is about 90 MeV below the nominal ∆∆ threshold of 2 m ∆ and its width of only 70 MeV is much less than the 2 Γ ∆ expected from the conventional t-channel ∆∆ process. Based on angular distributions the quantum numbers I(J P ) = 0(3 + ) have been assigned. In the double-pionic fusion reaction dd → 4 Heπ 0 π 0 again the ABC effect is observed to be correlated with the appearance of a resonance-like structure in the total cross section at the same excess energy. From this we conclude that this resonance structure obviously is strong enough to survive even in nuclei.

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Section: Introductionsupporting

confidence: 80%

Section: Discussion Of Resultsmentioning

confidence: 68%

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ABC Effect in Double-Pionic Fusion – a New Resonance?

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Bashkanov

Clement

et al. 2012

EPJ Web of Conferences

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“…For these the values 2.75 fm, 1.75 fm and +5.4 fm have been used. Whereas the latter two conform to the experimentally known values for effective range and scattering length, the value of R has been taken to be identical to the one used in pp induced two-pion production [52].…”

Section: Description Of the D * (2380) Resonance Processmentioning

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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“…The program started out with measurements of two-pion production in proton-proton collisions from close to threshold up to T p = 1.4 GeV ( √ s = 2.5 GeV) [9][10][11][12][13][14][15][16][17]. Special attention was paid to the ppπ 0 π 0 channel, where the previous bubble-chamber results suggested a kink in the total cross section around T p = 1.2 GeV.…”

Section: Proton-proton Induced Two-pion Productionmentioning

confidence: 99%

Recent Results from WASA-at-COSY

Clement¹,

Moskal²,

Skurzok³

2017

Proceedings of the 14th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU2016)

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The detector system WASA-at-COSY has been operated at the Cooler Synchrotron COSY in the years from 2006 till 2015. In this article we report on recent results of the analyses of the meson production reactions in nucleon-nucleon, nucleon-deuteron and deuteron-deuteron collisions with spin-polarized and unpolarized beams emphasizing the evidences for the existence of the dibaryon state in the proton-neutron system and the perspectives for the search of the η-mesic helium.

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ΔΔ excitation in proton–proton induced π0π0 production

Cited by 40 publications

References 62 publications

ABC Effect in Double-Pionic Fusion – a New Resonance?

ABC Effect in Double-Pionic Fusion – a New Resonance?

Examination of the nature of the ABC effect

Recent Results from WASA-at-COSY

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