Search for the QCD critical point in nuclear collisions at 158A GeV at the CERN Super Proton Synchrotron (SPS)
Author(s)Roland, Christof E.; Roland, Gunther M.
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Pion production in nuclear collisions at the Super Proton Synchrotron (SPS) is investigated with the aim to search, in a restricted domain of the phase diagram, for power laws in the behavior of correlations that are compatible with critical QCD. We analyzed interactions of nuclei of different sizes (p+p, C+C, Si+Si, Pb+Pb) at 158A GeV adopting, as appropriate observables, scaled factorial moments in a search for intermittent fluctuations in transverse dimensions. The analysis is performed for π+π- pairs with an invariant mass very close to the two-pion threshold. In this sector one may capture critical fluctuations of the sigma component in a hadronic medium, even if the σ meson has no well-defined vacuum state. It turns out that for the Pb+Pb system the proposed analysis technique cannot be applied without entering the invariant mass region with strong Coulomb correlations. As a result the treatment becomes inconclusive in this case. Our results for the other systems indicate the presence of power-law fluctuations in the freeze-out state of Si+Si approaching in size the prediction of critical QCD.
DepartmentMassachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Physical Review C
American Physical Society
NA49 Collaboration et al. “Search for the QCD critical point in nuclear collisions at 158A GeV at the CERN Super Proton Synchrotron (SPS).” Physical Review C 81.6 (2010): 064907. © 2010 The American Physical Society.
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