A new concept of clustering is discussed in A hypernuclei using a new-type microscopic cluster model wave function, which has a structure in which constituent clusters are confined in a container, whose size is a variational parameter and which we refer to as a hyper-Tohsaki-Horiuchi-Schuck-Röpke (hyper-THSR) wave function. By using the hyper-THSR wave function, the 2α + A-cluster structure in 9ΛBe is investigated. We show that full microscopic solutions in the 2α + A-cluster system, which are given as 2α + A Brink-GCM (generator coordinate method) wave functions, are almost perfectly reproduced by the single configurations of the hyper-THSR wave function. The squared overlaps between both wave functions are calculated to be 99.5%, 99.4%, and 97.7% for Jπ = 0+, 2+, and 4+ states, respectively. We also simulate the structural change by adding the A particle, by varying the ΛN interaction artificially. With the increase of the AN interaction, the A particle gets to move more deeply inside the core and strongly invokes the spatial core shrinkage. Accordingly, distinct localized 2α clusters appear in the nucleonic intrinsic density, though, in the 8Be nucleus, a gaslike 2α-cluster structure is shown. The origin of the localization is associated with the strong effect of the Pauli principle. We conclude that the container picture of the 2α and A clusters is essential in understanding the cluster structure in 9ΛBe, in which the very compact spatial localization of clusters is shown in the density distribution.
ASJC Scopus subject areas
- Physics and Astronomy(all)