Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A note on the cosmological constant problem   An speculative solution for the cosmological constant problem is proposed. It
is argued that while the true quantum vacuum energy density is of the order of
$M_P^4$, the observed classical vacuum energy density may be much smaller due
to the huge amount of scattering process in the vacuum state of quantum
gravity.

18
The categories of this paper are: econ
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn