Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anomalous behavior in the phonon dispersion of the (001) surface of
  Bi$_2$Te$_3$ determined from helium atom-surface scattering measurements   We employ inelastic helium atom-surface scattering to measure the low energy
phonon dispersion along high-symmetry directions on the surface of the
topological insulator Bi$_2$Te$_3$. Results indicate that one particular
low-frequency branch experiences noticeable mode softening attributable to the
interaction between Dirac fermion quasiparticles and phonons on the surface.
This mode softening constitutes a renormalization of the real part of the
phonon self-energy. We obtain the imaginary part, and hence lifetime
information, via a Hilbert transform. In doing so we are able to calculate an
average branch specific electron-phonon coupling constant $<\lambda_\nu> =
1.44$.

31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con