Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Low Energy Antiproton Experiments -- A Review   Low energy antiprotons offer excellent opportunities to study properties of
fundamental forces and symmetries in nature. Experiments with them can
contribute substantially to deepen our fundamental knowledge in atomic, nuclear
and particle physics. Searches for new interactions can be carried out by
studying discrete symmetries. Known interactions can be tested precisely and
fundamental constants can be extracted from accurate measurements on free
antiprotons ($\bar{p}$'s) and bound two- and three-body systems such as
antihydrogen ($\bar{{\rm H}}=\bar{p}e^-$), the antprotonic helium ion (He$^{++}
\bar{p}$)$^+$ and the antiprotonic atomcule (He$^{++} \bar{p}e^-$) . The
trapping of a single $\bar{p}$ in a Penning trap, the formation and precise
studies of antiprotonic helium ions and atoms and recently the production of
$\bar{{\rm H}}$ have been among the pioneering experiments. They have led
already to precise values for $\bar{p}$ parameters, accurate tests of bound
two- and three-body Quantum Electrodynamics (QED), tests of the CPT theorem and
a better understanding of atom formation from their constituents. Future
experiments promise more precise tests of the standard theory and have a robust
potential to discover new physics.

11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat