Lvy-stable two-pion Bose-Einstein correlations in GeV AuAu collisions

Adare, A.*; Hasegawa, Shoichi  ; Nagamiya, Shoji; Sako, Hiroyuki  ; Sato, Susumu ; Tanida, Kiyoshi  ; PHENIX Collaboration*; 448 of others*

We present a detailed measurement of charged two-pion correlation functions in 0%-30% centrality GeV AuAu collisions by the PHENIX experiment at the Relativistic Heavy Ion Collider. The data are well described by Bose-Einstein correlation functions stemming from Lvy-stable source distributions. Using a fine transverse momentum binning, we extract the correlation strength parameter , the Lvy index of stability and the Lvy length scale parameter as a function of average transverse mass of the pair . We find that the positively and the negatively charged pion pairs yield consistent results, and their correlation functions are represented, within uncertainties, by the same Lvy-stable source functions. The measurements indicate a decrease of the strength of the correlations at low . The Lvy length scale parameter decreases with increasing , following a hydrodynamically predicted type of scaling behavior. The values of the Lvy index of stability are found to be significantly lower than the Gaussian case of , but also significantly larger than the conjectured value that may characterize the critical point of a second-order quark-hadron phase transition.