Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of cyclotron resonance and measurement of the hole mass in
  optimally-doped La$_{2-x}$Sr$_{x}$CuO$_4$   Using time-domain terahertz spectroscopy in pulsed magnetic fields up to 31
T, we measure the terahertz optical conductivity in an optimally-doped thin
film of the high temperature superconducting cuprate
La$_{1.84}$Sr$_{0.16}$CuO$_4$. We observe systematic changes in the
circularly-polarized complex optical conductivity that are consistent with
cyclotron absorption of p-type charge carriers characterized by a cyclotron
mass of $4.9\pm 0.8$ $m_{\rm e}$, and a scattering rate that increases with
magnetic field. These results open the door to studies aimed at characterizing
the degree to which electron-electron interactions influence carrier masses in
cuprate superconductors.

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The categories of this paper are: stat
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The categories of this paper are: q-fin
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
1
The categories of this paper are: cs
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The categories of this paper are: eess
37
The categories of this paper are: supr-con