Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Strong dineutron correlation in 8He and 18C   We study the spatial structure of four valence neutrons in the ground state
of $^8$He and $^{18}$C nuclei using a core+4$n$ model. For this purpose, we
employ a density-dependent contact interaction among the valence neutrons, and
solve the five-body Hamiltonian in the Hartree-Fock-Bogoliubov (HFB)
approximation. We show that two neutrons with the coupled spin of $S$=0 exhibit
a strong dineutron correlation around the surface of these nuclei, whereas the
correlation between the two dineutrons is much weaker. Our calculation
indicates that the probability of the (1p$_{3/2})^4$ and [(1p$_{3/2})^2$
(p$_{1/2})^2$] configurations in the ground state wave function of $^8$He
nucleus is 34.9% and 23.7%, respectively. This is consistent with the recent
experimental finding with the $^8$He($p,t)^6$He reaction, that is, the ground
state wave function of $^8$He deviates significantly from the pure
(1p$_{3/2})^4$ structure.

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The categories of this paper are: funct-an
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat