Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantization of systems with time-dependent constraints. Example of
  relativistic particle in plane wave   A modification of the canonical quantization procedure for systems with
time-dependent second-class constraints is discussed and applied to the
quantization of the relativistic particle in a plane wave. The time dependence
of constraints appears in the problem in two ways. The Lagrangian depends on
time explicitly by origin, and a special time-dependent gauge is used. Two
possible approaches to the quantization are demonstrated in this case. One is
to solve directly a system of operator equations, proposed by Tyutin and one of
the authors (Gitman) as a generalization of Dirac canonical quantization in
nonstationary case, and another to find first a canonical transformation, which
makes it possible to discribe the dynamics in the physical sactor by means of
some effective Hamiltonian. Quantum mechanics constructed in both cases proves
to be equivalent to Klein-Gordon theory of the relativistic particle in a plane
wave. The general conditions of unitarity of the dynamics in the physical
sector are discussed.

24
The categories of this paper are: dg-ga
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom