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let us consider two quite different equations of state ( eos ) of nuclear matter within a _ true _ relativistic hydrodynamic framework ( i.e. , hylander - c ) @xcite .
the first one , eos - i , has a phase - transition to a qgp at @xmath3 = 200 @xmath4 ( @xmath5 = 1.35 @xmath6 ) @xcite .
the second eos , eos - ii , is a purely hadronic eos , which has been extracted from the transport code rqmd ( cf . ,
@xcite ) under the assumption of fully acchieved thermalization .
if one assumes for each eos _ different _ initial conditions before the hydrodynamical expansions , one can fit simultaneously hadronic single inclusive momentum spectra and bec , which have been measured recently by the cern / na44 and cern / na49 collaborations ( cf . , @xcite ) , respectively .
in particular , for the acceptance of the na44 experiment a ratio @xmath7 1.15 was found @xcite while using both eos , eos - i and eos - ii .
little difference was seen in the bec of identical pion pairs while considering the two different eos .
in the following , we shall assume for central au+au collisions at bnl / rhic beam energies a set of fireball initial conditions , ic - i , which are similar to those as described in ref .
@xcite . from these fireball initial conditions , ic - i , single inclusive momentum spectra have been calculated while using eos - i and eos - ii in the hydrodynamic expansions .
we note , that the rapidity spectra of both calculations differ in width and nomalization significantly @xcite .
shows , that the isothermes of the transversely expanding fluids at longitudinal coordinate @xmath8 also differ significantly .
since there will be only one set of measured data , we shall fit the calculation using eos - ii to the single inclusive momentum spectra of the calculation using eos - i . in doing so , we find new initial conditions , ic - ii @xcite .
but now the space - time picture of the evolving fireball at freeze - out is again very similar to the one using eos - i with ic - i .
if one calculates bec of identical pion pairs or identical kaon pairs , resepectively , one finds @xcite while comparing the calculations using eos - i with ic - i and eos - ii with ic - ii , respectively , _ no _ significant differences in the extracted ratios @xmath0 regardless of the pair kinematics under consideration .
in particular , the assumption of the phenix detector acceptance @xcite leads to a ratio @xmath7 1.65 for both choices of eos .    in summary
, the larger ratio @xmath0 at rhic beam energies appears to be rather a consequence of the expected higher energy deposit in the fireball during the heavy - ion collision , but it appears _ not _ to be an indicator of the present or absent phase - transition to a qgp .
of course , more theoretical analysis is neccessary , but there is strong evidence , that bec do not provide a good qgp signature , since we do not understand the initial state of a heavy - ion collision well enough yet
.    9 d.h .
rischke , m. gyulassy , nucl .
a608 ( 1996 ) 479 .
g. bertsch , m. gong , m. tohyama , phys .
c37 ( 1988 ) 1896 .
schlei , heavy ion phys . 5 ( 1997 ) 403 .
schlei , et al . , to appear in eur .
j. c10/1 ( 1999 ) .
schlei , d. strottman , n. xu , phys .
80 ( 1998 ) 3467 , and refs . therein .
check the web - site http://www.nis.lanl.gov/@xmath10bschlei/qm99.html b.r .
schlei , d. strottman , phys .
c59 ( 1999 ) r9 .
+ in 1996 , d.h . 
 rischke and m. gyulassy @xcite proposed to use the time - delay signal in bose - einstein correlations ( bec ) as a signature for the possible formation of a quark - gluon plasma ( qgp ) in relativistic heavy - ion collisions . in particular 
 , they suggested to measure the ratio of the transversal interferometry radii , @xmath0 , which can be obtained by fitting experimental bec data with a parametrization introduced by g. bertsch @xcite et al . in 1988 . 
 the transverse radius parameter @xmath1 has compared to the transverse radius parameter @xmath2 an additional temporal dependence which should be sensitive to a prolonged lifetime of a fireball , in case a qgp was formed in a relativistic heavy - ion collision . 
 this latter phenomenon is known under the term `` qgp stall '' . in the following , 
 i shall explain why i believe that the time - delay signal in bose - einstein correlations _ is not _ a good signature for the possible formation of a qgp .