Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charged-particle multiplicity measurement in proton-proton collisions at
  $\sqrt{s}$ = 7 TeV with ALICE at LHC   The pseudorapidity density and multiplicity distribution of charged particles
produced in proton-proton collisions at the LHC, at a centre-of-mass energy
$\sqrt{s} = 7$ TeV, were measured in the central pseudorapidity region |$\eta$|
< 1. Comparisons are made with previous measurements at $\sqrt{s}$ = 0.9 TeV
and 2.36 TeV. At $\sqrt{s}$ = 7 TeV, for events with at least one charged
particle in |$\eta$| < 1, we obtain dNch/deta = 6.01 $\pm$ 0.01 (stat.)
$^{+0.20}_{-0.12}$ (syst.). This corresponds to an increase of 57.6% $\pm$ 0.4%
(stat.) $^{+3.6}_{-1.8}$% (syst.) relative to collisions at 0.9 TeV,
significantly higher than calculations from commonly used models. The
multiplicity distribution at 7 TeV is described fairly well by the negative
binomial distribution.

24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th