Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Empirical Determination of the Very High Energy Heavy Quark Cross
  Section from Non-Accelerator Data   To cosmic rays incident near the horizon the Earth's atmosphere represents a
beam dump with a slant depth reaching 36000~g~cm$^{-2}$ at $90^\circ$. The
prompt decay of a heavy quark produced by very high energy cosmic ray showers
will leave an unmistakable signature in this dump. We translate the failure of
experiments to detect such a signal into an upper limit on the heavy quark
hadroproduction cross section in the energy region beyond existing
accelerators. Our results disfavor any rapid growth of the cross section or the
gluon structure function beyond very conservative estimates based on
perturbative QCD.

11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci