TY - JOUR
T1 - Measurement of the pn → ppπ0π- Reaction in Search of the ABC Resonance
AU - Skorodko, T.
AU - Bashkanov, M.
AU - Clement, H.
AU - Doroshkevich, E.
AU - Perez Del Rio, E.
AU - Pricking, A.
AU - Wagner, G. J.
PY - 2012/12/1
Y1 - 2012/12/1
N2 - With pd collisions at Tp = 1.2 GeV exclusive measurements of the quasi-free pn → ppπ0π- reaction have been carried out. Using the WASA detector setup at COSY total and differential cross sections have been obtained for the energy region √s = 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 π0π--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, δ(1600) and δδ 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 γ = 70 MeV and I(JP) = 0(3 +), which was recently observed in the pn → dπ 0π0 reaction, leads to a much improved description of the data at low energies.
AB - With pd collisions at Tp = 1.2 GeV exclusive measurements of the quasi-free pn → ppπ0π- reaction have been carried out. Using the WASA detector setup at COSY total and differential cross sections have been obtained for the energy region √s = 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 π0π--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, δ(1600) and δδ 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 γ = 70 MeV and I(JP) = 0(3 +), which was recently observed in the pn → dπ 0π0 reaction, leads to a much improved description of the data at low energies.
UR - http://www.scopus.com/inward/record.url?scp=84883119293&partnerID=8YFLogxK
U2 - 10.1051/epjconf/20123709033
DO - 10.1051/epjconf/20123709033
M3 - Article
AN - SCOPUS:84883119293
SN - 2101-6275
VL - 37
JO - EPJ Web of Conferences
JF - EPJ Web of Conferences
M1 - 09033
ER -