L
vy-stable two-pion Bose-Einstein correlations in
GeV Au
Au 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 Au
Au collisions by the PHENIX experiment at the Relativistic Heavy Ion Collider. The data are well described by Bose-Einstein correlation functions stemming from L
vy-stable source distributions. Using a fine transverse momentum binning, we extract the correlation strength parameter
, the L
vy index of stability
and the L
vy 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 L
vy-stable source functions. The
measurements indicate a decrease of the strength of the correlations at low
. The L
vy length scale parameter
decreases with increasing
, following a hydrodynamically predicted type of scaling behavior. The values of the L
vy 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.