Excitation of the Roper resonance in single- and double-pion production in nucleon-nucleon collisions⋆

Skorodko, T.; Bashkanov, M.; Bogoslawsky, D.; Calén, H.; Cappellaro, F.; Clement, H.; Demiroers, L.; Doroshkevich, E.; Duniec, D.; Ekström, C.; Franssen, K.; Gustafsson, L.; Höistad, B.; Ivanov, G.; Jacewicz, M.; Jiganov, E.; Johansson, T.; Khakimova, O.; Kaskulov, M.; Keleta, S.; Koch, I.; Kren, F.; Kullander, S.; Kupść, A.; Кузнецов, А. А.; Marciniewski, P.; Meier, R.; Morosov, B.; Pauly, C.; Petterson, Henrik; Petukhov, Y.; Povtorejko, A.; Schönning, K.; Scobel, W.; Shwartz, B.; Sopov, V.; Stepeniak, J.; Thörngren-Engblom, P.; Tikhomirov, V.; Wagner, Gerhard; Wolke, M.; Yamamoto, A.; Zabierowski, J.; Złomańczuk, J.

doi:10.1140/epja/i2008-10569-6

Cited by 60 publications

(44 citation statements)

References 9 publications

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“…3) -in agreement with the observations in all other two-pion channels of pp initiated reactions [15,16,17,18,19,20,21,23,24,25,26] and properly reproduced by conventional calculations of the t-channel ∆∆ process [22,14].…”

Section: Pos(bormio 2013)013supporting

confidence: 86%

See 1 more Smart Citation

Encounters with Di-Baryons - from the ABC Effect to a New Resonance?

Río¹

2013

Proceedings of 51st International Winter Meeting on Nuclear Physics — PoS(Bormio 2013)

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The ABC effect, an intriguing low-mass enhancement in the ππ invariant mass spectrum, is known from inclusive measurements of two-pion production in nuclear fusion reactions to the few-body systems d, 3 He and 4 He. It was first observed 1960 by Abashian, Booth and Crowe in the inclusive pd → 3 He X reaction. Its explanation has been a puzzle since then. In an effort to solve this long-standing problem by exclusive and kinematically complete high-statistics experiments, we have measured the fusion reactions to d, 3 He and 4 He with WASA-at-COSY. These measurements cover the full energy region, where the ABC effect has been observed previously in inclusive reactions. In a recent kinematically complete measurement of the pn → dπ 0 π 0 reaction we have shown that the ABC effect in this basic double-pionic fusion reaction is correlated with a narrow structure in the total cross section with quantum numbers I(J P ) = 0(3 + ), a mass of 2.37 GeV and a width of about 70 MeV. The mass is about 90 MeV below 2 times the mass of ∆, the mass of a ∆∆ system, and the width is three times narrower than expected from a conventional t-channel ∆∆ process. In the double-pionic fusion reaction to the helium isotope 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 a previous exclusive experiment at CELSIUS-WASA it is known that the double-pionic fusion to 3 He also exhibits a pronunced ABC effect. New data from COSY on the pd → 3 Heπ 0 π 0 reaction scanning the full ABC region are presented as well as the status of measurements in other reaction channels, where the new resonance might contribute.

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Section: Pos(bormio 2013)013supporting

confidence: 86%

“…These measurements cover the full energy region, where the ABC effect has been observed previously in inclusive reactions. They complement the systematic two-pion production measurements carried out at PROMICE/WASA [15,16,17], CELSIUS/WASA [13,18,19,20,21,27,28], COSY-TOF [23,24], COSY-MOMO [29], WASA-at-COSY [25,30,31] and COSY-ANKE [26].…”

Section: Methodsmentioning

confidence: 82%

Encounters with Di-Baryons - from the ABC Effect to a New Resonance?

Río¹

2013

Proceedings of 51st International Winter Meeting on Nuclear Physics — PoS(Bormio 2013)

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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%

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

Pricking

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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“…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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Excitation of the Roper resonance in single- and double-pion production in nucleon-nucleon collisions⋆

Cited by 60 publications

References 9 publications

Encounters with Di-Baryons - from the ABC Effect to a New Resonance?

Encounters with Di-Baryons - from the ABC Effect to a New Resonance?

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

Recent Results from WASA-at-COSY

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