Forward-AngleH3e(e,e′

Abstract

Forward-angle coincident electroproduction cross sections of charged pions from 3 He have been measured at electron energies E 0 855, 675, 600, and 555 MeV. The overall features of the data for energy transfers of v 370 to 430 MeV with pions detected along the momentum transfer axis are reproduced in terms of a microscopic model, including pole terms, final state rescattering and produced and preformed D resonances. Separation of the cross section into its longitudinal and transverse parts was performed at Q 2 0.045 ͑GeV͞c͒ 2 . The longitudinal part of the cross section in the p 1 channel does not contradict with the assumption of a preformed D 11 . [S0031-9007(96)01208-2]

Search for the Δ++ component in the C ground state using the C(γ,π+p) reaction

“…[10]. Results for the reaction 3 He(e, e ′ π ± ) obtained at MAMI do not contradict the assumption that a preformed ∆ ++ contributes to the reaction yield [11]. As for the processes with real photons, only the measurements of 12 C(γ, π + p) and 3 He(γ, π ± p) reactions have been reported in Refs.…”

“…To analyze the data for E e = 500 MeV, we took into account the background from the double pion production in the 12 C(γ, pπ + π − ) 11 B reaction, which was absent at E e = 420 MeV. This photoabsorption mechanism is not included in the Valencia model.…”

“…under the assumption that the residual nucleus 11 Be is in its ground state. In order to estimate the error connected with this assumption, we have repeated the calculation considering the residual nucleus to be excited with the energy E x = 20 MeV.…”

A study of the Δ−-component of the wave function in light nuclei

“…[15,16] However, experimental searches for measurable consequences of ∆ components in the three-nucleon system using electroproduction have been inconclusive. [17,18,19] Recently, a new method for measuring the ∆ − component of the nuclear wave function has been suggested and has yielded results which are in agreement with the predictions of meson models of nuclear binding for range of nuclei. [20,21] This method is based on pion double charge exchange (DCX) which cannot occur in a single step if the pion interacts with nucleons.…”

Self energies of the pion and the Δ isobar from the 3He(e,e′π+)3H reaction

“…The specific experimental arrangements of the present experiment, including that of the cryogenic gas target and the data acquisition and analyses methods are described in detail in [5]. The very high missing mass resolution of δM ≈ 700 keV/c 2 (FWHM) is quite adequate [5][6][7][8] to clearly isolate the coherent channel ( 3 Hπ + ) from the three-and four-body final states (ndπ + ) and (nnpπ + ).…”