Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Wigner-Eckart theorem and Jordan-Schwinger representation for
  infinite-dimensional representations of the Lorentz group   The Wigner-Eckart theorem is a well known result for tensor operators of
SU(2) and, more generally, any compact Lie group. This paper generalises it to
arbitrary Lie groups, possibly non-compact. The result relies on knowledge of
recoupling theory between finite-dimensional and arbitrary admissible
representations, which may be infinite-dimensional; the particular case of the
Lorentz group will be studied in detail. As an application, the Wigner-Eckart
theorem will be used to construct an analogue of the Jordan-Schwinger
representation, previously known only for finite-dimensional representations of
the Lorentz group, valid for infinite-dimensional ones.

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The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex