Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Impurity states in multiband s-wave superconductors: analysis of iron
  pnictides   We examine the effect of a single, non-magnetic impurity in a multiband,
extended s-wave superconductor allowing for anisotropy of the gaps on the Fermi
surfaces. We derive analytic expressions for the Green's functions in the
continuum and analyse the conditions for the existence of sharp
impurity-induced resonant states. Underlying band structure is more relevant
for the multiband than for single band case, and mismatch between the bands
generically makes the formation of the impurity states less likely in the
physical regime of parameters. We confirm these conclusions by numerically
solving the impurity problem in a tight-binding parameterization of the bands
relevant to pnictide superconductors.

21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ