Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hexagonal warping on optical conductivity of surface states in
  Topological Insulator Bi_{2}Te_{3}   ARPES studies of the protected surface states in the Topological Insulator $%
Bi_{2}Te_{3}$ have revealed the existence of an important hexagonal warping
term in its electronic band structure. This term distorts the shape of the
Dirac cone from a circle at low energies to a snowflake shape at higher
energies. We show that this implies important modifications of the interband
optical transitions which no longer provide a constant universal background as
seen in graphene. Rather the conductivity shows a quasilinear increase with a
slightly concave upward bending as energy is increased. Its slope increases
with increasing magnitude of the hexagonal distortion as does the magnitude of
the jump at the interband onset. The energy dependence of the density of states
is also modified and deviates downward from linear with increasing energy.

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The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat