Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effect of the coupling to a superconductor on the level statistics of a
  metal grain in a magnetic field   A theory is presented for the statistics of the excitation spectrum of a
disordered metal grain in contact with a superconductor. A magnetic field is
applied to fully break time-reversal symmetry in the grain. Still, an
excitation gap of the order of $\delta$ opens up provided $N\Gamma^2\gtrsim 1$.
Here $\delta$ is the mean level spacing in the grain, $\Gamma$ the tunnel
probability through the contact with the superconductor, and $N$ the number of
transverse modes in the contact region. This provides a microscopic
justification for the new random-matrix ensemble of Altland and Zirnbauer.

29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys