Proton 2p-2h intruder excitations and the modified vibrational intensity and selection rules

It is pointed out that strong mixing between proton two-particle two-hole (2p-2h) $0^{+}$, $2^{+}$, intruder configurations, and the quadrupole phonon vibrational states modifies the original quadrupole vibrational intensity and selection rules. This approach explains the possibility for certain states to exhibit apparently both intruder and vibrational characteristics and results mainly from strong mixing of the $0^{+}$ states. We present interacting boson model calculations and compare in detail, for ${}_{}{}^{114}{}_{}{}^{}\mathrm{Cd}$, the quintuplet of levels near ${\mathit{E}}_{\mathit{x}}$≃1.2 MeV.