Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effective Hamiltonian approach to optical activity in Weyl spin-orbit
  system   Chirality or handedness in condensed matter induces anomalous optical
responses such as natural optical activity, rotation of the plane of light
polarization, as a result of breaking of spatial-inversion symmetry. In this
study, optical properties of a Weyl spin-orbit system with quadratic
dispersion, a typical chiral system invariant under time-reversal, are
investigated theoretically by deriving an effective Hamiltonian based on an
imaginary-time path-integral formalism. We show that the effective Hamiltonian
can be indeed written in terms of an optical chirality order parameter
suggested by Lipkin. The natural optical activity is discussed based on the
Hamiltonian.

3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
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The categories of this paper are: hep-th
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
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The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
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The categories of this paper are: econ
36
The categories of this paper are: cmp-lg