Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anisotropic ultrafast electron dynamics induced by high-field terahertz
  pulses in n-doped InGaAs   The anisotropic effective mass of electrons is directly measured using
time-resolved THz- pump/THz-probe techniques in a n-doped InGaAs semiconductor
thin film. A microscopic theory is used to attribute this anisotropy in the THz
probe transmission to the nonparabolicity of the conduction band.
Self-consistent light-matter coupling is shown to contribute significantly to
the THz response.

8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph