Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Time-Reversal Invariant Topological Phase at the Surface of a 3D
  Topological Insulator   A 3D fermionic topological insulator has a gapless Dirac surface state
protected by time-reversal symmetry and charge conservation symmetry. The
surface state can be gapped by introducing ferromagnetism to break
time-reversal symmetry, introducing superconductivity to break charge
conservation, or entering a topological phase. In this paper, we construct a
minimal gapped topological phase that preserves both time-reversal and charge
conservation symmetries and supports Ising-type non-Abelian anyons. This phase
can be understood heuristically as emerging from a surface s-wave
superconducting state via the condensation of eight-vortex composites. The
topological phase inherits vortices supporting Majorana zero modes from the
surface superconducting state. However, since it is time-reversal invariant,
the surface topological phase is a distinct phase from the Ising topological
phase, which can be viewed as a quantum-disordered spin-polarized p_x + i p_y
superconductor. We discuss the anyon model of this topological phase and the
manner in which time-reversal symmetry is realized in it. We also study the
interfaces between the topological state and other surface gapped phases.

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The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an