Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A column of grains in the jamming limit: glassy dynamics in the
  compaction process   We investigate a stochastic model describing a column of grains in the
jamming limit, in the presence of a low vibrational intensity. The key control
parameter of the model, $\epsilon$, is a representation of granular shape,
related to the reduced void space. Regularity and irregularity in grain shapes,
respectively corresponding to rational and irrational values of $\epsilon$, are
shown to be centrally important in determining the statics and dynamics of the
compaction process.

3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin