Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quadrupole Moments of Collective Structures up to Spin $\sim$ $65\hbar$
  in $^{157}$Er and $^{158}$Er: A Challenge for Understanding Triaxiality in
  Nuclei   The transition quadrupole moments, $Q_{\rm t}$, of four weakly populated
collective bands up to spin $\sim$ $65\hbar$ in $^{157,158}$Er have been
measured to be ${\sim}11 {\rm eb}$ demonstrating that these sequences are
associated with large deformations. However, the data are inconsistent with
calculated values from cranked Nilsson-Strutinsky calculations that predict the
lowest energy triaxial shape to be associated with rotation about the short
principal axis. The data appear to favor either a stable triaxial shape
rotating about the intermediate axis or, alternatively, a triaxial shape with
larger deformation rotating about the short axis. These new results challenge
the present understanding of triaxiality in nuclei.

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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
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The categories of this paper are: physics
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The categories of this paper are: eess
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The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
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The categories of this paper are: stat
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg