Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A unified theory of superconductivity   In this paper, we study the reliability of BCS theory as a scientific
explanation of the mystery of superconductivity. It is shown clearly that the
phonon-mediated BCS theory is fundamentally incorrect. Two kinds of glues,
pairing (pseudogap) glue and superconducting glue, are suggested based on a
real space Coulomb confinement effect. The scenarios provide a unified
explanation of the pairing symmetry, pseudogap and superconducting states,
charge stripe order, spin density wave (SDW), checkerboard-type charge-ordered
phase, magic doping fractions and vortex structures in conventional and
unconventional (the high-Tc cuprates and MgB2) superconductors. The theory
agrees with the existence of a pseudogap in high-temperature superconductors,
while no pseudogap feature could be observed in MgB2 and most of the
conventional superconductors. Our results indicate that the superconducting
phase can coexist with a inclined hexagonal vortex lattice in pure MgB2 single
crystal with a charge carrier density ps=1.49*10^{22}/cm^{3}. Finally, the
physical reasons why the good conductors (for example, Ag, Au, and Cu) and the
overdoped high-Tc superconductors are non-superconducting are also explored.

15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex