Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Is the analysis of flow at the CERN SPS reliable?   Several heavy ion experiments at SPS have measured azimuthal distributions of
particles with respect to the reaction plane. These distributions are deduced
from two-particle azimuthal correlations under the assumption that they result
solely from correlations with the reaction plane. In this paper, we investigate
other sources of azimuthal correlations: transverse momentum conservation,
which produces back-to-back correlations, resonance decays, HBT correlations
and final state interactions. These correlations increase with impact
parameter: most of them vary with the multiplicity N like 1/N. When they are
taken into account, the experimental results of the NA49 collaboration at SPS
are significantly modified. These correlations might also explain an important
fraction of the pion directed flow observed by WA98. Data should be reanalyzed
taking into account carefully these non--flow correlations.

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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: mtrl-th
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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: q-alg
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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: astro-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio