2013/06/30 by P. Adlarson, W. Augustyniak, W. Bardan +121 · 3 citations
Chemistry · Physics and Astronomy · #Atomic physics #Chemistry #Crystallography #Energy (signal processing) #Isovector #Nuclear physics #Nuclear physics research studies #Nucleon #Particle physics #Particle physics theoretical and experimental studies #Physics #Pion #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Resonance (particle physics) #nucl-ex
paper · pdf · doi:10.1103/physrevc.88.055208
arxiv created 2013/11/12 · openalex publication_date 2013/11/26 · arxiv updated 2015/06/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Exclusive measurements of the quasifree pn\ensuremath→pp\ensuremathπ0\ensuremathπ^\ensuremath- reaction have been performed by means of pd collisions at Tp = 1.2 GeV using the wide angle shower apparatus (WASA) detector setup at the cooler synchrotron COSY (Institut f"ur Kernphysik, J"ulich). Total and differential cross sections have been obtained covering the energy region √(s) = (2.35--2.46) GeV, which includes the region of the ABC effect and its associated resonance structure. No ABC effect, i.e., low-mass enhancement is found in the \ensuremathπ0\ensuremathπ^\ensuremath--invariant mass spectrum, in agreement with the constraint from Bose statistics that the isovector pion pair can not be in relative s wave. At the upper end of the covered energy region t-channel processes for Roper, \ensuremathΔ(1600) and \ensuremathΔ\ensuremathΔ excitations provide a reasonable description of the data, but at low energies the measured cross sections are much larger than predicted by such processes. Adding a resonance amplitude for the resonance at m = 2.37 GeV with \ensuremathΓ = 70 MeV and I(JP)=0(3+) observed recently in pn\ensuremath→d\ensuremathπ0\ensuremathπ0 and pn\ensuremath→d\ensuremathπ+\ensuremathπ^\ensuremath- reactions leads to an agreement with the data also at low energies.