Exchange current effects in pion double charge exchange from4He

Germond, Jean‐François; Wilkin, C.

doi:10.1007/bf02745898

Cited by 46 publications

(17 citation statements)

References 11 publications

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“…1(a) [11,18] and on the alternative mechanisms illustrated in Figs. 1(b) [15], and 1(c) and 1(d) [19] have not achieved quantitative success in reproducing the available data [1,3,4, 19 -23]. Until recently, the theoretical literature on DCX in heavier nuclei was very sparse [24 -26].…”

Section: Introductionmentioning

confidence: 99%

Systematics of inclusive pion double charge exchange in the delta resonance region

et al. 1992

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A systematic study of inclusive pion double charge exchange is reported for nuclei between A = 16 and A =208. The doubly differential cross sections for the A(m. +,~) and A(m, m+) reactions in ' 0, Ca, ' Rh, and 'Pb were measured at incident energies between 120 and 270 MeV at three to five outgoing pion angles. Pion spectra were measured over the energy range from 10 MeV to the kinematic limit for double charge exchange. Integrating these spectra over outgoing pion energy generated angular distributions, and subsequently integrating these angular distributions generated total reaction cross sections. The shapes of the measured spectra are compared with those determined by the distribution of events in four-body phase space and with those predicted by a model in which the pion undergoes two sequential single charge exchanges on nucleons in a Fermi gas. The cross sections are compared with predictions of cascade calculations in which more than two interactions, including pion absorption and scattering without charge exchange, may occur. PACS number(s): 25.80.Gn, 25.80. Hp, 25.80.Ls major objective was to satisfy persistent curiosity about 'Present address: Continuous Beam Electron Accelerator Facility,

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Section: Introductionmentioning

confidence: 99%

Systematics of inclusive pion double charge exchange in the delta resonance region

et al. 1992

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“…These low values of the cross section, produced by the mechanism that dominates the reaction below the pion-production threshold and at resonance, open the possibility for alternative mechanisms such as the MEC to be revealed. The MEC mechanism, in which the incoming pion scatters with a virtual pion of opposite charge in the "cloud" surrounding the target nucleon of the nucleus and is itself absorbed on another nucleon, was first proposed by Germond and Wilkin [10] and consists of the assumption that the incident pion is scattered on the off-shell pion exchanged by the nucleons within the nucleus and the DCX takes place at the ππ vertex. The pole diagram in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…This is due to the strong distortion of the pion waves at resonance on the one hand and a variety of mechanisms that play a significant role on the other. Explaining the energy dependence of DCX has led to a diversity of proposed mechanisms, including the successive delta interaction mechanism [8,9], the meson exchange current (MEC) mechanism [10,11], the six-quark bag mechanism [12], absorption mechanisms [13], dibaryon mechanisms [14], assuming the production of the hypothetical d dibaryon, a resonance with baryon number B = 2 in the pNN subsystem, and others involving more than two nucleons.…”

Section: Introductionmentioning

confidence: 99%

Pion double charge exchange in a composite-meson model

Kezerashvili¹,

Boyko

2007

Phys. Rev. C

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The pion double charge exchange amplitude is evaluated in a composite-meson model based on the four-quark interaction. The model assumes that the mesons are two-quark systems and can interact with each other only through quark loops. To evaluate the meson exchange current contribution, the form factors of the two-pion decay modes of the ρ, σ , and f 0 mesons have been used in the calculations. The contribution of the four-quark box diagram has been taken into account as well as a contact diagram. The contributions of the ρ, σ , and f 0 mesons increase the forward scattering cross section, which depends weakly on the energy.

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“…Germond and Wilkin [5] suggested a different mechanism for DCX reaction, the interaction of the incident pion with the exchange current meson or pions in the cloud surrounding each nucleon. Their calculations did not include the Pauli effect or Fermi motion of the nucleons.…”

Section: Introductionmentioning

confidence: 99%

Pion double charge exchange onHe4

et al. 1977

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The doubly differential cross sections for the 4 He(π + , π − )4p reaction were calculated using both a two-nucleon sequential single charge exchange model and an intranuclear cascade code. Final state interactions between the two final protons which were the initial neutrons were included in both methods. At incident pion energies of 240 and 270 MeV the low-energy peak observed experimentally in the energy spectrum of the final pions can be understood only if the contribution of pion production is included. The calculated cross sections are compared with data.

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Exchange current effects in pion double charge exchange from4He

Cited by 46 publications

References 11 publications

Systematics of inclusive pion double charge exchange in the delta resonance region

Systematics of inclusive pion double charge exchange in the delta resonance region

Pion double charge exchange in a composite-meson model

Pion double charge exchange onHe4

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