Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Proposed astrophysical test of Lorentz invariance   Working in the context of a Lorentz-violating extension of the standard model
we show that estimates of Lorentz symmetry violation extracted from ultra-high
energy cosmic rays beyond the Greisen-Kuzmin-Zatsepin (GZK) cutoff allow for
setting bounds on parameters of that extension. Furthermore, we argue that a
correlated measurement of the difference in the arrival time of gamma-ray
photons and neutrinos emitted from active galactic nuclei or gamma-ray bursts
may provide a signature of possible violation of Lorentz symmetry. We have
found that this time delay is energy independent, however it has a dependence
on the chirality of the particles involved. We also briefly discuss the known
settings where the mechanism for spontaneous violation of Lorentz symmetry in
the context of string/M-theory may take place.

17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom