Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the origin of the anomalous behaviour of 2+ excitation energies in
  the neutron-rich Cd isotopes   Recent experimental results obtained using $\beta$ decay and isomer
spectroscopy indicate an unusual behaviour of the energies of the first excited
2$^{+}$ states in neutron-rich Cd isotopes approaching the N=82 shell closure.
To explain the unexpected trend, changes of the nuclear structure far-off
stability have been suggested, namely a quenching of the N=82 shell gap already
in $^{130}$Cd, only two proton holes away from doubly magic $^{132}$Sn. We
study the behaviour of the 2$^+$ energies in the Cd isotopes from N=50 to N=82,
i.e. across the entire span of a major neutron shell using modern beyond mean
field techniques and the Gogny force. We demonstrate that the observed low
2$^+$ excitation energy in $^{128}$Cd close to the N=82 shell closure is a
consequence of the doubly magic character of this nucleus for oblate
deformation favoring thereby prolate configurations rather than spherical ones.

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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
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The categories of this paper are: ao-sci
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The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
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The categories of this paper are: acc-phys
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The categories of this paper are: physics
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: nlin
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The categories of this paper are: cs
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph