Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A lattice evaluation of four-quark operators in the nucleon   Nucleon matrix elements of various four-quark operators are evaluated in
quenched lattice QCD using Wilson fermions. Some of these operators give rise
to twist-four contributions to nucleon structure functions. Furthermore, they
bear valuable information about the diquark structure of the nucleon. Mixing
with lower-dimensional operators is avoided by considering appropriate
representations of the flavour group. We find that for a certain flavour
combination of baryon structure functions, twist-four contributions are very
small. This suggests that twist-four effects for the nucleon might be much
smaller than m_p^2/Q^2.

22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs