Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Test of Lorentz invariance in $\beta$ decay of polarized
  $^{20}\text{Na}$   We search for a dependence of the lifetime of $^{20}\text{Na}$ nuclei on the
nuclear spin direction. Such a directional dependence would be evidence for
Lorentz-invariance violation in weak interactions. A difference in lifetime
between nuclei that are polarized in the east and west direction is searched
for. This difference is maximally sensitive to the rotation of the Earth, while
the sidereal dependence is free from most systematic errors. The experiment
sets a limit of $2\times 10^{-4}$ at 90 % C.L. on the amplitude of the sidereal
variation of the relative lifetime differences, an improvement by a factor 15
compared to an earlier result.

24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th