Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the spectral gap in Andreev graphs   We introduce Andreev scattering (electron-hole conversion at an interface of
a normal conductor to a superconductor) at the outer vertices of a quantum star
graph and examine its effect on the spectrum. More specifically we show that
the density of states in Andreev graphs is suppressed near the Fermi energy
where a spectral gap may occur. The size and existence of such a gap depends on
one side on the Andreev scattering amplitudes and, on the other side,on the
properties of the electron-electron scattering matrix at the central vertex. We
also show that the bond length fluctuations have a minor effect on the spectrum
near the Fermi energy.

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The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
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The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph