Measurement of the p n ---> p p pi0 pi- reaction in search of the ABC resonance
2012 (English)In: Proceedings of 12th International Workshop on Production, properties and interaction of mesons (MESON 2012) / [ed] Aleksandra Wronska, Roman Skibinski, Carlo Guaraldo, Stanislaw Kistryn, Hans Stroeher, Les Ulis Cedex, France: EDP Sciences, 2012, 09033- p.Conference paper (Other academic)
With pd collisions at T_p = 1.2 GeV exclusive measurements of the quasi-free pn -> pppi^0pi^- reaction have been carried out. Using the WASA detector setup at COSY total and differential cross sections have been obtained for the energy region &radics = 2.35 - 2.48 GeV. Though this includes the region of the ABC effect and its associated resonance structure, no low-mass enhancement (ABC effect) is found in the pi^0pi^--invariant mass spectrum - in agreement with the constraint from Bose statistics demanding the isovector pion pair to be in relative p-wave. Conventional calculations including t-channel processes for Roper, Delta(1600) and DeltaDelta excitations and their decays, which are well-known from the study of the two-pion production in pp collisions, provide a reasonable description of the data at high energies, but fall low at low energies. From this we conclude that a large contribution from a so far unknown isoscalar low-energy process is missed in the calculations. Inclusion of the ABC resonance at m = 2.37 GeV with Gamma = 70 MeV and I(J^P) = 0(3^+), which was recently observed in the pn -> dpi^0pi^0 reaction, leads to a much improved description of the data at low energies.
Place, publisher, year, edition, pages
Les Ulis Cedex, France: EDP Sciences, 2012. 09033- p.
, EPJ Web of Conferences, ISSN 2100-014X (Electronic Edition) ; 37
Research subject Nuclear Physics
IdentifiersURN: urn:nbn:se:uu:diva-196967DOI: 10.1051/epjconf/2012370903333OAI: oai:DiVA.org:uu-196967DiVA: diva2:611368
12th International Workshop on Meson Production, Properties and Interaction (MESON 2012)