Δ isobar in nuclei (review of experimental data)

10.1007/s11450-008-1010-2

“…Calculations and dedicated experiments revealed that this mechanism must broaden the delta-resonance peak in a nucleus and shift it toward higher excitation energies in relation to the free delta isobar [18]. That the shift of the delta-isobar masses toward lower values and the narrowing of the delta resonances in relation to the free delta isobar were discovered in the present study is likely to suggest the existence of a mechanism in a nucleus other than the quasifreecollective mechanism of delta isobar excitation.…”

“…It should be recalled that, in early investigations, quasifree delta-isobar production on one of the intranuclear nucleons was assumed to be a dominant mechanism of the delta excitation of nuclei [18]. Calculations and dedicated experiments revealed that this mechanism must broaden the delta-resonance peak in a nucleus and shift it toward higher excitation energies in relation to the free delta isobar [18].…”

“…That the shift of the delta-isobar masses toward lower values and the narrowing of the delta resonances in relation to the free delta isobar were discovered in the present study is likely to suggest the existence of a mechanism in a nucleus other than the quasifreecollective mechanism of delta isobar excitation. This mechanism is associated with the response of a nucleus as a discrete unit rather than with a spinisospin excitation of one intranuclear nucleon [18,19].…”