Monopole excitation to cluster states
Strength of monopole excitation to cluster states is discussed in light nuclei. A detail analysis of 12C, typical in light nuclei, leads to the fact that the monopole excitation to cluster states is in general so strong to be comparable to the single particle strength and shares an appreciable portion of the sum rule value, in spite of large difference of the structure between the cluster state and the shell-model-like ground state. The present results imply that the measurement of strong monopole transitions or excitations is generally very useful for the study of cluster states.