Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dilepton/Photon Production in Heavy Ion Collisions and the QCD Phase
  Transition   We calculate electromagnetic production from highly excited hadronic matter
created in heavy ion collisions. The rates include the usual lowest order
processes in quark-gluon plasma plus the usual reactions in the hadronic phase,
related with rho,a_1 mesons. The space-time integration is done using a
hydrodynamical model. We have found that dilepton mass spectrum agrees with
results of other previous works, but *disagrees* with the CERES dilepton data.
In order to explain these data, some "unconventional" production mechanism need
to be incorporated: we discuss especially the notion of modified rho,a_1
masses, which indeed may explain the data. Other suggestions (e.g. the
longer-lived fireball) to increase the production of low mass dileptons seem to
be insufficient for the task. The results for direct photon production are
below the current WA80 experimental bounds, for all variants considered.

33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org