Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exact analytical solution of a time-reversal-invariant topological
  superconducting wire   We consider a model proposed before for a time-reversal-invariant topological
superconductor (TRITOPS) which contains a hopping term $t$, a chemical
potential $\mu$, an extended $s$-wave pairing $\Delta$ and spin-orbit coupling
$\lambda$. We show that for $|\Delta|=|\lambda|$, $\mu=t=0$, the model can be
solved exactly defining new fermion operators involving nearest-neighbor sites.
The many-body ground state is four-fold degenerate due to the existence of two
zero-energy modes localized exactly at the first and the last site of the
chain. These four states show entanglement in the sense that creating or
annihilating a zero-energy mode at the first site is proportional to a similar
operation at the last site. By continuity, this property should persist for
general parameters. Using these results we correct some statements related with
the so called "time-reversal anomaly". Addition of a small hopping term for a
chain with an even number of sites breaks the degeneracy and the ground state
becomes unique with an even number of particles. We also consider a small
magnetic field applied to one end of the chain. We compare the many-body
excitation energies and spin projection along the spin-orbit direction for both
ends of the chains with numerical results %for a small chain obtaining good
agreement.

6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con