Isospin decomposition of the basic double-pionic fusion in the region of the ABC effect

WASA-at-COSY Collaboration, P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, T. Bednarski, F. S. Bergmann, M. Berlowski, H. Bhatt, M. Buescher, H. Calen, H. Clement*, D. Coderre, E. Czerwinski, K. Demmich, E. Doroshkevich, R. Engels, W. Erven, W. Eyrich, P. FedoretsK. Foehl, K. Fransson, F. Goldenbaum, P. Goslawski, A. Goswami, K. Grigoryev, C-O Gullstrom, F. Hauenstein, L. Heijkenskjold, V. Hejny, F. Hinterberger, M. Hodana, B. Hoistad, A. Jany, B. R. Jany, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, F. A. Khan, A. Khoukaz, S. Kistryn, J. Klaja, H. Kleines, B. Klos, M. Krapp, W. Krzemien, P. Kulessa, A. Kupsc, K. Lalwani, L. Li

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Exclusive and kinematically complete high-statistics measurements of the basic double-pionic fusion reactions pn -> d pi(0)pi(0), pn -> d pi(+)pi(-) and pp -> d pi(+)pi(0) have been carried out simultaneously over the energy region of the ABC effect using the WASA detector setup at COSY. Whereas the isoscalar reaction part given by the d pi(0)pi(0) channel exhibits the ABC effect, i.e. a low-mass enhancement in the pi pi-invariant mass distribution, as well as the associated resonance structure in the total cross section, the isovector part given by the d pi(+)pi(0) channel shows a smooth behavior consistent with the conventional t-channel Delta Delta process. The d pi(+)pi(-) data are very well reproduced by combining the data for isovector and isoscalar contributions, if the kinematical consequences of the isospin violation due to different masses for charged and neutral pions are taken into account. (C) 2013 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)229-236
Number of pages8
JournalPhysics Letters B
Issue number4-5
Publication statusPublished - 25 Apr 2013

Keywords / Materials (for Non-textual outputs)

  • ABC effect and resonance structure
  • Double pion production
  • lsospin decomposition
  • GEV-C
  • PP


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