Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Empirical pairing gaps, shell effects, and di-neutron spatial
  correlation in neutron-rich nuclei   The empirical pairing gaps derived from four different odd-even mass
staggering formulas are compared. By performing single-$j$ shell and
multi-shell seniority model calculations as well as by using the standard HFB
approach with Skyrme force we show that the simplest three-point formula
$\Delta_C^ {(3)}(N)=\frac{1}{2}\left[B(N,Z)+B(N-2,Z)-2B(N-1,Z)\right]$ can
provide a good measure of the neutron pairing gap in even-$N$ nuclei. It
removes to a large extent the contribution from the nuclear mean field as well
as contributions from shell structure details. It is also less contaminated by
the Wigner effect for nuclei around $N=Z$. We also show that the strength of
$\Delta^ {(3)}_C(N)$ can serve as a good indication of the two-particle spatial
correlation in the nucleus of concern and that the weakening of $\Delta^
{(3)}_C(N)$ in some neutron-rich nuclei indicates that the di-neutron
correlation itself is weak in these nuclei.

9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio