Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Tests of Lorentz symmetry using antihydrogen   Signals of CPT and Lorentz violation are possible in the context of
spectroscopy using hydrogen and antihydrogen. We apply the Standard-Model
Extension, a broad framework for Lorentz breaking in physics, to various
transitions in the hydrogen and antihydrogen spectra. The results show an
unsuppressed effect in the transition between the upper two hyperfine sublevels
of the ground state of these systems. We also discuss related tests in Penning
traps, and recent work on Lorentz violation in curved spacetime.

26
The categories of this paper are: bayes-an
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The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th