Evidence of centrality dependent fractal behavior in high energy heavy ion interactions: Hint of two different sources

Studies on large density fluctuations in produced particle spectra in high energy interactions provide enough information regarding the dynamics of the process of particle production. Various analyses have revealed self-similarity in particle production process. The concept of self-similarity is indicative of fractal geometry. The present analysis reports an exhaustive study on centrality dependence of event-by-event fluctuation of pions produced in16O-AgBr interactions at 60 A GeV using a non conventional tool based on complex network analysis, viz. visibility graph method. The analysis reveals different fractal behaviour as well as different clustering property for different centrality events and the amount of fractality and average clustering coefficient decrease with the increase of centrality. Estimation of Hurst exponent hints towards two different sources of fluctuation, fractional Brownian motion (fBm) and fractional Gaussian noises (fGn) for two different centrality classes.