Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Center of mass energy and system-size dependence of photon production at
  forward rapidity at RHIC   We present the multiplicity and pseudorapidity distributions of photons
produced in Au+Au and Cu+Cu collisions at \sqrt{s_NN} = 62.4 and 200 GeV. The
photons are measured in the region -3.7 < \eta < -2.3 using the photon
multiplicity detector in the STAR experiment at RHIC. The number of photons
produced per average number of participating nucleon pairs increases with the
beam energy and is independent of the collision centrality. For collisions with
similar average numbers of participating nucleons the photon multiplicities are
observed to be similar for Au+Au and Cu+Cu collisions at a given beam energy.
The ratios of the number of charged particles to photons in the measured
pseudorapidity range are found to be 1.4 +/- 0.1 and 1.2 +/- 0.1 for
\sqrt{s_NN} = 62.4 GeV and 200 GeV, respectively. The energy dependence of this
ratio could reflect varying contributions from baryons to charged particles,
while mesons are the dominant contributors to photon production in the given
kinematic region. The photon pseudorapidity distributions normalized by average
number of participating nucleon pairs, when plotted as a function of \eta -
ybeam, are found to follow a longitudinal scaling independent of centrality and
colliding ion species at both beam energies.

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The categories of this paper are: physics
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The categories of this paper are: cond-mat
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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio
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The categories of this paper are: math-ph
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The categories of this paper are: hep-th
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: q-fin
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The categories of this paper are: stat