The low-lying collective states of xenon isotopes are studied by means of the boson expansion theory. The microscopic Hamiltonian is comprised of the self-consistent QQ interaction with higher-order (three- and four-body) terms, monopole- and quadrupole-pairing interactions in addition to the spherical limit of the Nilsson Hamiltonian. It is shown that the difficulty of weak strengths of the monopole-pairing interaction in this region, indicated by Rohoziński et al., can be naturally remedied by including the quadrupole-pairing interactions. © 1995 The American Physical Society.