Excitation energy dependence of pion fluctuation: an in-depth study

Abstract

This paper investigates the so-called excitation energy dependence (i.e. classification of fluctuation pattern of pions on the basis of number of grey tracks) at different projectile energies. The different data sets thus obtained correspond to different degrees of target excitation. The fluctuation pattern of pions is studied in two dimensions considering anisotropy of phase space. The parameter characterizing the anisotropy of phase is the Hurst exponent. The analysis is performed using a very rigorous method by fitting one-dimensional second-order factorial moment saturation curves. The study reveals that the effective fluctuation strength depends on target excitation. It is also observed that the target excitation dependence of fluctuation of pions is different at different projectile energies. Recent investigations of the RHIC data have revealed the fact that the behaviour of multiplicity fluctuations with collision centrality is non-monotonic. Our investigation also reveals the same fact.