Systematic study of two-pion production in NN collisions- from single-baryon to Di-baryon excitations

TY - GEN

T1 - Systematic study of two-pion production in NN collisions- from single-baryon to Di-baryon excitations

AU - Skorodko, T.

AU - Bashkanov, M.

AU - Clement, H.

AU - Doroshkevich, E.

AU - Khakimova, O.

AU - Kren, F.

AU - Pricking, A.

AU - Wagner, G. J.

PY - 2010/9/22

Y1 - 2010/9/22

N2 - The two-pion production in nucleon-nucleon collisions has been studied by exclusive and kinematically complete experiments from threshold up to T p = 1.36 GeV at CELSIUS-WASA. At near-threshold energies the total and differential distributions for the π+π- and π0π 0 channels are dominated by Roper excitation and its decay into Nσ and Δπ channels. At beam energies Tp > 1.1 GeV the ΔΔ excitation governs the two-pion production process. In the π+π+ channel evidence is found for the excitation of a higher-lying I=3/2 resonance, favorably the Δ(1600). The isovector fusion processes leading to the deuteron and to quasi-stable 2He, respectively, exhibit no or only a modest ABC-effect, i.e. low-mass enhancement in the ππ-invariant mass spectrum, and can be described by conventional t-channel ΔΔ excitation. On the other hand, the isoscalar fusion process to the deuteron exhibits a dramatic ABC-effect correlated with a narrow resonance-like energy dependence in the total cross section with a width of only 50 MeV and situated at a mass 90 MeV below the ΔΔ mass.

AB - The two-pion production in nucleon-nucleon collisions has been studied by exclusive and kinematically complete experiments from threshold up to T p = 1.36 GeV at CELSIUS-WASA. At near-threshold energies the total and differential distributions for the π+π- and π0π 0 channels are dominated by Roper excitation and its decay into Nσ and Δπ channels. At beam energies Tp > 1.1 GeV the ΔΔ excitation governs the two-pion production process. In the π+π+ channel evidence is found for the excitation of a higher-lying I=3/2 resonance, favorably the Δ(1600). The isovector fusion processes leading to the deuteron and to quasi-stable 2He, respectively, exhibit no or only a modest ABC-effect, i.e. low-mass enhancement in the ππ-invariant mass spectrum, and can be described by conventional t-channel ΔΔ excitation. On the other hand, the isoscalar fusion process to the deuteron exhibits a dramatic ABC-effect correlated with a narrow resonance-like energy dependence in the total cross section with a width of only 50 MeV and situated at a mass 90 MeV below the ΔΔ mass.

KW - Δ Δ excitation

KW - Δ (1600)

KW - ABC effect and resonance

KW - Roper excitation

UR - http://www.scopus.com/inward/record.url?scp=77956698512&partnerID=8YFLogxK

U2 - 10.1063/1.3483384

DO - 10.1063/1.3483384

M3 - Conference contribution

AN - SCOPUS:77956698512

SN - 9780735408074

VL - 1257

SP - 520

EP - 524

BT - Hadron 2009 - Proceedings of the XIII International Conference on Hadron Spectroscopy

T2 - 13th International Conference on Hadron Spectroscopy, Hadron 2009

Y2 - 29 November 2009 through 4 December 2009

ER -