Improved intermittency analysis of proton density fluctuations in NA49 ion collisions at 158 AGeV

Nikolaos G Antoniou,Nikolaos N Davis,The Na49 Collaboration ,Fotios K Diakonos

doi:10.1051/epjconf/20147100035

Nikolaos G Antoniou, Nikolaos N Davis + Show 2 more

Open Access

https://doi.org/10.1051/epjconf/20147100035

Copy DOI

Abstract

The existence of the QCD critical point is a controversial issue, which is ex- pected to be clarified in current ion collision experiments. In the vicinity of the criti- cal point, according to recent theoretical investigations, the chiral condensate (chiral or- der 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 conden- sate 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 (spuri- ous correlations) in the analysed data sets.

Highlights

We calculate the second factorial moment of the proton density, in transverse momentum recorded in stphaecNe,Afr4o9mexdpatearismetesnotfa“tSmi”a+xSimi (u“mSi”e=neArgl,ySi(,P√),sN“CN ”≈+C17(“GC”e=VC),oNf)tahnedSPPbS+(PCbEcRoNlli)s.ioWnes concentrate on the development of a methodological framework allowing the consistent treatment of uncertainties related to arbitrary bin boundary placement and the possible presence of split tracks in the data
In a pure critical system, the presence of intermittency in transverse momentum space can be revealed by calculating the dependence of the Second Scaled Factorial Moments (SSFMs) of proton tracks as a function of bin size
Intermittency analysis of density fluctuations in transverse momentum space is an important tool for the detection of critical behaviour in QCD

Summary

Introduction

EPJ Web of Conferences fluctuations are transferred to the net proton density, as well as to the proton and antiproton densities separately, which are experimentally accessible [17]. We calculate the second factorial moment of the proton density, in transverse momentum recorded in stphaecNe,Afr4o9mexdpatearismetesnotfa“tSmi”a+xSimi (u“mSi”e=neArgl,ySi(,P√),sN“CN ”≈+C17(“GC”e=VC) ,oNf)tahnedSPPbS+(PCbEcRoNlli)s.ioWnes concentrate on the development of a methodological framework allowing the consistent treatment of uncertainties related to arbitrary bin boundary placement and the possible presence of split tracks in the data

The Analysed data sets

Intermittency Analysis Methodology

Analysis Results

Conclusions