Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Statistical Mechanics of Vacancy and Interstitial Strings in Hexagonal
  Columnar Crystals   Columnar crystals contain defects in the form of vacancy/interstitial loops
or strings of vacancies and interstitials bounded by column ``heads'' and
``tails''. These defect strings are oriented by the columnar lattice and can
change size and shape by movement of the ends and forming kinks along the
length. Hence an analysis in terms of directed living polymers is appropriate
to study their size and shape distribution, volume fraction, etc. If the
entropy of transverse fluctuations overcomes the string line tension in the
crystalline phase, a string proliferation transition occurs, leading to a
supersolid phase. We estimate the wandering entropy and examine the behaviour
in the transition regime. We also calculate numerically the line tension of
various species of vacancies and interstitials in a triangular lattice for
power-law potentials as well as for a modified Bessel function interaction
between columns as occurs in the case of flux lines in type-II superconductors
or long polyelectrolytes in an ionic solution. We find that the centered
interstitial is the lowest energy defect for a very wide range of interactions;
the symmetric vacancy is preferred only for extremely short interaction ranges.

18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: math
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
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The categories of this paper are: q-fin
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The categories of this paper are: physics
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The categories of this paper are: hep-ex