Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Prompt, pre-equilibrium, and thermal photons in relativistic nuclear
  collisions   The direct photon emission model in relativistic nuclear colliders has been
improved in recent years for reducing the discrepancy between theoretical
estimations and experimental data and for understanding the properties of the
QCD matter. In this study, the contribution of pre-equilibrium photons are
investigated in addition to those of prompt and thermal photons in the
framework of a relativistic hydrodynamic model. The numerical simulations at an
LHC energy suggest that the pre-equilibrium photons may be relevant at
intermediate transverse momentum near the saturation momentum scale, increasing
particle spectra and reducing elliptic flow of direct photons.

10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin