Περίληψη:
The existence of the QCD critical point is a controversial issue, which
is expected to be clarified in current ion collision experiments. In the
vicinity of the critical point, according to recent theoretical
investigations, the chiral condensate (chiral order parameter) should
exhibit critical fluctuations (self-similarity and scale-invariance).
These fluctuations should also be present in the transverse momentum
distributions of protons produced in ion collision experiments due to
the coupling of the chiral condensate with the net-proton density.
We use intermittency analysis to calculate the 2nd scaled factorial
moment (SSFM) of transverse momenta of protons produced around
mid-rapidity in central A+A collisions at the NA49 experiment
(SPS,CERN). Three different systems are analysed (C+C, Si+Si and Pb+Pb).
We develop techniques in order to improve the traditional intermittency
approach, estimating the level of non-critical background and correcting
for systematic methodological errors that arise in the case of low
statistics. We find evidence of power-law dependence of the SSFM
(intermittency) in the case of Si+Si and Pb+Pb systems. Furthermore, we
perform a suitable correlation analysis in order to test and rule out
the possibility that the observed behaviour is influenced by
misidentified split tracks (spurious correlations) in the analysed data
sets.
Συγγραφείς:
Antoniou, Nikolaos G.
Davis, Nikolaos N.
Diakonos, Fotios K. and
NA49 Collaboration
