Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Euclidean formulation of relativistic quantum mechanics   In this paper we discuss a formulation of relativistic quantum mechanics that
uses Euclidean Green functions or generating functionals as input. This
formalism has a close relation to quantum field theory, but as a theory of
linear operators on a Hilbert space, it has many of the advantages of quantum
mechanics. One interesting feature of this approach is that matrix elements of
operators in normalizable states on the physical Hilbert space can be
calculated directly using the Euclidean Green functions without performing an
analytic continuation. The formalism is summarized in this paper. We discuss
the motivation, advantages and difficulties in using this formalism. We discuss
how to compute bound states, scattering cross sections, and finite Poincare
transformations without using analytic continuation. A toy model is used to
demonstrate how matrix elements of exp(-beta H) in normalizable states can be
used to construct-sharp momentum transition matrix elements.

22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
2
The categories of this paper are: math