Multiplicity fluctuation and phase transition in high-energy collision — A chaos-based study with complex network perspective

Abstract

Multiplicity fluctuation provides enough information concerning the dynamics of particle production process and even signature of phase transition from hadronic to QGP phase expected in ultrarelativistic nuclear collision. Numerous analyses reported on the fluctuation pattern of pions have been studied from theoretical and phenomenological approaches. Also the fractal properties have been explored to characterize quantitative degree of fluctuation. The present work reports a study of pion fluctuation from a radically different perspective, using science of complexity. For this we have taken two different interactions — one hadron–nucleus and other nucleus–nucleus, namely [Formula: see text]-AgBr (350 GeV) and [Formula: see text]S-AgBr (200 A[Formula: see text]GeV). We have analyzed both data in the light of complex network analysis, viz. visibility graph method. The data reveal that power of the scale-freeness in visibility graph (PSVG), a quantitative parameter related to Hurst exponent, may provide information on the degree of fluctuation. Further, in a recent work, it was shown that phase transition can also be studied using the same methodology. Based on the result of the present study we further propose to use this methodology, where critical phenomena are to be assessed — even in case of pion fluctuation, for obtaining the QGP like phase transition.