Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Breakdown of the Hard Thermal Loop expansion near the light-cone   We discuss the bremsstrahlung production of soft real and virtual photons in
a quark-gluon plasma at thermal equilibrium beyond the Hard Thermal Loop (HTL)
resummation. The physics is controlled by the ratio $Q^2/q_0^2$ of the
virtuality to the energy. When $Q^2/q_0^2$ is much smaller than $g^2$, where
$g$ is the strong coupling constant, the emission rate is enhanced by a factor
$1/g^2$ over the HTL results due to light-cone singularities and the
bremsstrahlung is induced by scattering of the quark via both transverse and
longitudinal soft gluon exchanges. When $Q^2/q_0^2$ increases, the enhancement
factor is given by $q_0^2/Q^2$. When this ratio is near unity, the
bremsstrahlung contribution is of the same order as the rate predicted by the
HTL resummation. In that case, the bremsstrahlung is induced by both soft and
hard gluon exchanges.

23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas