Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultra High Energy Cosmic Rays: Strangelets? -- Extra dimensions,
  TeV-scale black holes and strange matter   The conjecture that ultra high energy cosmic rays (UHECRs) are actually
strangelets is discussed. Besides the reason that strangelets can do as cosmic
rays beyond the GZK-cutoff, another argument to support the conjecture is
addressed in this letter via the study of formation of TeV-scale microscopic
black holes when UHECRs bombarding bare strange stars. It is proposed that the
exotic quark surface of a bare strange star could be an effective
astro-laboratory in the investigations of the extra dimensions and of the
detection of ultra-high energy neutrino fluxes. The flux of neutrinos (and
other point-like particles) with energy >2.3 x 10^{20} eV could be expected to
be smaller than 10^{-26} cm^{-2}$ s^{-1} if there are two extra spatial
dimensions.

18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg