Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonequilibrium effects in the tunneling conductance spectra of small
  metallic particles   The tunneling spectra of small metallic grains shows an unusual structure of
the differential conductance peaks. Namely, resonance peaks appear in clusters,
or develop substructure as the the gate voltage is changed. These features are
manifestations of a nonequilibrium behavior which appears when the applied
source-drain voltage is sufficiently large. Electron-electron Coulomb
interaction as well as an attractive pairing interaction play an important role
in determining the magnitude and energy scales of the phenomena. For normal
grains each cluster of resonances is identified with one excited
single-electron state of the metal particle, shifted as a result of the
different nonequilibrium occupancy configurations of the other single-electron
states. For superconducting grains in the odd charging state, the substructure
of the resonance is explained by nonequilibrium ``gapless'' excitations
associated with different energy levels occupied by the unpaired electron. The
excitations are generated by inelastic cotunneling.

7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th