Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The London penetration depth of strongly coupled isotropic
  superconductors : low temperature behaviour   We proceed to a systematic exploration of the low temperature dependence of
the London penetration depth of isotropic superconductors within strong
coupling theory in the clean limit. For a sizeable range of parameters, we find
that strong coupling effects can reasonably simulate a power law dependence,
sometimes with an excellent precision. In such cases it would be quite
difficult to distinguish experimentally between a pure power law and the strong
coupling result. Physically we have been able to ascribe this temperature
dependence to low frequency phonons which produce a quasi elastic scattering
for electrons. The presence of these low frequency phonons requires rather wide
phonon spectra and their effectiveness in scattering implies fairly strong
coupling.

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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an