Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Proton Stability in Six Dimensions   We show that Lorentz and gauge invariance explain the long proton lifetime
within the standard model in six dimensions. The baryon-number violating
operators have mass dimension 15 or higher. Upon TeV-scale compactification of
the two universal extra dimensions on a square $T^2/Z_2$ orbifold, a discrete
subgroup of the 6-dimensional Lorentz group continues to forbid dangerous
operators.

9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga