Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Non-Relativistic Groundstate Energy of Positronium in
  Relativistic Schroedinger Theory   The \emph{Relativistic Schr\"odinger Theory} (RST) has been set up as an
alternative form of particle theory. This theory obeys the fundamental
symmetries which are required to hold for any meaningful theory: gauge and
Lorentz covariance (RST can be formulated even over a pseudo-Riemannian
space-time). But the question is now whether obeying those fundamental
symmetries is sufficient for the practical success of a theory, i.e. whether
the predictions are in agreement with the experimental findings. In this
context, the non-relativistic energy spectrum of positronium has been
considered in some precedent papers. Here, the problem is that exact solutions
of the RST eigenvalue system cannot be obtained and one has to resort to
approximate solutions. For this purpose, a variational method is applied in the
present paper which yields the RST groundstate energy smaller than the former
results and than its conventional counterpart by some 10\%. Such deviations are
also observed when one compares the approximate RST spectrum (up to quantum
numbers $n\approx 100$) to the corresponding predictions of the conventional
theory. It seems presently not possible to decide whether those deviations are
due to RST itself or are merely due to the applied approximation technique.
Thus the practical usefulness of RST must remain unclarified for the moment.

6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
16
The categories of this paper are: stat
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph