Role of α-cluster structure in electric-dipole excitations of ⁶Li

 ⁴He (α)-cluster structure often appears in light nuclei, for example, ⁶Li is well approximated by a three-body model of α + p + n [1]. Recently, the photoabsorption cross sections of ⁶Li was measured showing two-peak structure [2]. Since the reaction occurs mainly through the electric-dipole (E1) transition, the lower and higher peaks were conjectured as the giant dipole resonance (GDR) of ⁶Li and the GDR of α cluster in ⁶Li, respectively. If this conjecture is true, making its excitation mechanism clear is important because it can appear in the nuclei in which an α cluster is well developed.

 In this work, we perform a fully microscopic six-body calculation that can take the excitation of α cluster into account. We calculate the E1 transition strengths, E1 transition densities and α-spectroscopic factors in order to discuss the E1 excitation mechanism and the role of α cluster in ⁶Li.

References

[1] W. Horiuchi and Y. Suzuki, Phys. Rev. C 76, 024311 (2007)

[2] T. Yamagata et al., Phys. Rev. C 95, 044307 (2017)