Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scalar mesons in QCD and tests of the gluon content of the sigma   We summarize the different features of the scalar mesons from QCD spectral
sum rule analyses of the two- and three-point functions. The results do not
favour the u-bar u + d-bar d interpretation of the broad and low mass sigma
(0.6), and the u-bar s resonance nature of the eventually observed kappa(0.9)
meson. We also discuss some OZI-violating and classic semileptonic and
radiative decay processes which can reveal in a model-independent way the
eventual gluon component sigma_B of the sigma. In a meson-gluonium mixing
scenario, one also expects an observation of the K K-bar final states from the
sigma_B which may compete (if phase space allowed) with the one from a low mass
s-bar s state assumed in the literature to be the SU(3) partner of the $\sigma
(0.6)$ if this latter is a u-bar u + d-bar d state

27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys