Untersuchung von Resonanzen im Di-Baryon-System anhand von Daten zur Multi-Pionenproduktion und Neutron-Proton-Streuung
Zusammenfassung der Projektergebnisse
Summarizing we could finish up the analysis of WASA-at-COSY data regarding possible dibaryon formation and production in the course of nucleon-nucleon collisions. Besides of d*(2380), for which pole, mass, width and all hadronic decays have been determined meanwhile, evidence for another dibaryonic state with I(JP) = 2(1+) has been found, which is decoupled from the nucleon-nucleon system due to its isospin. Our analysis of differential cross section data for elastic neutron-proton scattering reconfirms impressively the findings of the analysis of the analyzing power data regarding the pole of d*(2380) in neutron-proton scattering. The attempt to retrieve meaningful information about photon decays of d*(2380) failed, however, due to computer crashes and loss of data. Fortunately, data about photo excitation of the deuteron obtained at MAMI and ELSA could shed new light on this issue. The question, whether d*(2380) constitutes a dilute molecular system or rather a compact hexaquark system, has been dealt with extensively in a review article, where we discuss this topic both from the experimental and from the theoretical point of view. A surprise in hadron physics of recent years was the recognition that in the flavored sector there are many multi-quark states in the region of thresholds. Since they are very narrow resonances, they are comparatively easy to detect. This situation is quite different from the unflavored sector, where the hadronic widths are large and hence such multi-quark resonances broad. From the lessons learned in the flavored sector this meant now for us the question, whether we have at the N*(1440)N threshold a similar phenomenon as at the ∆N threshold, where various dibaryon candidates – presumable of molecular character – have been found in the past. Our finding that the isoscalar single-pion production starts out near threshold with a rising cross section as expected, but then falls off beyond 2.30 GeV appeared as an ideal testing ground for this hypothesis. In a reanalysis of WASA-at-COSY data we clarified the bump nature of this cross section and its connection to the Roper excitation. Taking into account a previous partial-wave analysis we demonstrate that all available data for elastic scattering, single- and double-pion production would be consistent with the presence of two dibaryonic systems in the vicinity of the N*(1440)N threshold. Moreover, these resonances would fit perfectly into the scenario of a nucleon-nucleon interaction, where the short- and intermediate range part is generated by intermediate dibaryon formation in low-L partial waves – presenting a bridge between nucleonic and quarkonic degrees of freedom.
Projektbezogene Publikationen (Auswahl)
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Isotensor Dibaryon in the pp→ppπ+π− Reaction?. Physical Review Letters, 121(5).
Adlarson, P.; Augustyniak, W.; Bardan, W.; Bashkanov, M.; Bergmann, F. S.; Berłowski, M.; Bondar, A.; Büscher, M.; Calén, H.; Ciepał, I.; Clement, H.; Czerwiński, E.; Demmich, K.; Engels, R.; Erven, A.; Erven, W.; Eyrich, W.; Fedorets, P.; Föhl, K. ... & Żurek, M.
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Examination of the production of an isotensor dibaryon in the pp→ppπ+π− reaction. Physical Review C, 99(2).
Adlarson, P.; Augustyniak, W.; Bardan, W.; Bashkanov, M.; Bergmann, F. S.; Berłowski, M.; Bondar, A.; Büscher, M.; Calén, H.; Ciepał, I.; Clement, H.; Czerwiński, E.; Demmich, K.; Engels, R.; Erven, A.; Erven, W.; Eyrich, W.; Fedorets, P.; Föhl, K. ... & Żurek, M.
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Corrigendum to Isoscalar Single-Pion Production in the Region of Roper and d*(2380) Resonances. Phys. Lett. B 806 (2020) 135555
P. Adlarson & al.
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Differential cross sections for neutron-proton scattering in the region of the d*(2380) dibaryon resonance. Physical Review C, 102(1).
Adlarson, P.; Augustyniak, W.; Bardan, W.; Bashkanov, M.; Bergmann, F. S.; Berłowski, M.; Bhatt, H.; Büscher, M.; Calén, H.; Ciepał, I.; Clement, H.; Coderre, D.; Czerwiński, E.; Demmich, K.; Doroshkevich, E.; Engels, R.; Erven, A.; Erven, W.; Eyrich, W. ... & Żurek, M.
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Nature of S-wave NN interaction and dibaryon production at nucleonic resonance thresholds. The European Physical Journal A, 56(9).
Kukulin, V. I.; Rubtsova, O. A.; Platonova, M. N.; Pomerantsev, V. N.; Clement, H. & Skorodko, T.
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Role of the d⁎(2380) dibaryon in NN interaction. Physics Letters B, 801, 135146.
Kukulin, V.I.; Rubtsova, O.A.; Platonova, M.N.; Pomerantsev, V.N. & Clement, H.
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Dibaryons: Molecular versus compact hexaquarks *. Chinese Physics C, 45(2), 022001.
Clement, H. & Skorodko, T.
