1、2008.5.24,LHC - IOPP,1,A test of hydrodynamic behavior in the formed matter of relativistic heavy ion collisions,Wang Meijuan, Liu Lianshou, and Wu Yuanfang IOPP, Huazhong Normal University, Wuhan, China,MotivationA new measure -neighboring angular-bin multiplicity corr. pattern 3. A demonstration -
2、 the pattern of Au + Au coll. at 200 GeV generated by transport models 4. Experimental measure and expectations 5. Summary and conclusions,2008.5.24,LHC - IOPP,2,1. Motivation:, New form of a quark-gluon plasma is formed at RHIC, Large energy density achieved Jet energy loss in matter Collective beh
3、aviour observed, Perfect liquid , sQGP !,The mass-dependence of v2 at pT 2 GeV shows qualitatively agreement with ideal hydrodynamic flow.,M. Gyulassy, L. McLerran, Nucl. Phys. A750, 30-63(2005); B. Muller, Annu. Rev. Nucl. and Part. Phys.,1(2006). K. Adcox et al. (PHENIX Coll.), Nucl. Phys. A757, 1
4、84-283(2005); John Adams et al. (STAR Coll.), Nucl. Phys. A757, 102-183(2005);,2008.5.24,LHC - IOPP,3,1. Motivation:, Uncertain problems of idea hydrodynamics,EP side:,PHENIX, PRL 98, 162301(2007); PHOBOS, PRL 98, 242302(2007)., Quantitatively fit the mass dependence of v2 ., Cu + Cu collisions at 2
5、00 GeV.,TH side:,R. C. Hwa, arXiv: 0708.1508; R. C. Rudy, C. B.Yang, arXiv: 0801.2183.,D. V. Anchishkin, S. N. Yezhov, arXiv: 0804.1745.,Azimuthal anisotropy arising from ridges without rapid thermalization,Relativistic nucleus-nucleus collisions without hydrodynamics,T. S. Biro and B. Muller, Phys.
6、 Lett. B 578, 78(2004); M. Asakawa, S. A. Bass, B. Muller, and C. Nonaka, arXiv: 0803.2449; S. A. Voloshin, arXiv: 0805.1351., Centrality dependence of v2 /(nq) vs. KET/nq for Au + Au at 200GeV.,STAR, PRC 77, 054971(2008).,2008.5.24,LHC - IOPP,4,1. Motivation:, Arising question,Does the formed matte
7、r at RHIC really behave like hydrodynamic flow ?,2008.5.24,LHC - IOPP,5,1. Motivation:, Observed evidence,Elliptic Flow Parameter v2,coordinate-space-anisotropy momentum-space-anisotropy,out-of-plane direction,in-plane direction,v2 can not provide information on intrinsic interaction of formed matte
8、r!,2008.5.24,LHC - IOPP,6,1. Motivation:,Examing intrinsic interaction of the formed matter !, Solusion,If initial anisotropic pressure gradient is the only driver of elliptic flow, the intrinsic interaction should have the same anisotropy as its azimuthal distribution, i.e., in-plane like. (2) Othe
9、rwise, the interaction pattern should be different from its azimuthal distribution.,To find experimentally who really drivers elliptic flow !,A spatial-dependent bin-bin correlation is called for !,How to measure the intrinsic interaction ?,2008.5.24,LHC - IOPP,7,1. Motivation:, Conventional measure
10、s, 2, or 3-particle correlations, bin-bin correlations,They can not provide preferential direction of intrinsic interactions !,Average corr. of two particles separated by a certain angle, no matter where the two particles are in the azimuthal space. So no information on intrinsic spatial interaction
11、!,Spatially averaged bin-bin corr. in exploring self-similar fractality, where the system is supposed to be homogeneous, and only scaling in the shrinking of phase space is concerned.,2008.5.24,LHC - IOPP,8,2. A new measure, Neighboring angular-bin multiplicity corr. pattern:, Two bin corr.,Wu Yuanf
12、ang, Lianshou Liu, Yingdan Wang, Yuting Bai and Hongbo Liao, PRE71, 017103 (2005)., Neighboring angular-bin multiplicity corr. pattern,m1, m2 : the positions of the two bins in phase space nm : the measured content in the mth bin,It is a 3-dimentional plot !,: multiplicityin mth bin.,: the direction
13、 of reaction plane.,It measures the spatial distribution of nearby particles correlation,2008.5.24,LHC - IOPP,9,2. A new measure, Independent production,If the particles are produced independently in the whole phase space, then:,Where, multiplicity is produced by AMPT and its dis. is randomly given
14、according to cos(2).,No significant correlation in the case !,Tang Aihong private comm.,2008.5.24,LHC - IOPP,10,3. A demonstration,RQMD with hadron rescattering: A hadron-based transport model, where v2 0, but smaller than the data at RHIC.,AMPT with string melting :Parton cascade + hadron rescatter
15、ing are both included. It reproduces v2 (pt) data at RHIC.,H. Sorge, Phys. Rev. C52, 3291 (1995); Y. Lu et al. nucl-th/0602009.,Zi-Wei Lin, Che Ming Ko, Bao-An Li, Bin Zhang and Subrata Pal, Phys. Rev. C72, 064901,Relativistic transport models:,2008.5.24,LHC - IOPP,11, Corr. pattern of Au + Au at 20
16、0 GeV given by RQMD & AMPT:,3. A demonstration,Patterns of Au + Au at 200 GeV given by RQMD & AMPT:, The corr. patterns from thesetwo models are -cos2 (out-of-plane) like, opposite to cos2 (in-plane) like azimuthal distribution., This shows that the formed matter is in fact drived toward out-of-plan
17、e direction, rather then in-plane direction ! Some unknown, or unexpected interactions exist in the formed matter.,2008.5.24,LHC - IOPP,12,3. A demonstration,Centrality dependence of the corr. patterns:,1. cos2(in-plane) like in peripheral collisions 2. flat in mid-central collisions, 3. - cos2(out-
18、of-plane) like in near-central collisions., These reveal that two opposite intrinsic interactions coexist in the formed matter in these two models. This shows that anisotropic azimuthal distribution is not only driven by anisotropic expansion !,2008.5.24,LHC - IOPP,13, Possible origins of out-of-pla
19、ne preferential corr. pattern:,3. A demonstration,(1) Missing parts from transport equation to idea hydrodynamics,Non-linear collision terms,Anisotropic geometry,Out-of-plane correlation pattern,More central collision, the larger the number of partons, and the stronger the contributions from collisi
20、on terms.,Li Jiarong, Liu Lianshou, Wu Yuanfang,2008.5.24,LHC - IOPP,14,3. A demonstration,(2) Initial interactions in geometric space,The evolution of AMPT,(Meijuan Wang, Jiaxin Du, Wu Yuanfang),2008.5.24,LHC - IOPP,15,3. A demonstration,Azimuthal corr. pattern in momentum space,Trace the pattern i
21、n the evolusion of AMPT,Initial eccentricity translates to pt space via transport equ (2)Both patterns appear simultaneously. (3) From parton to hadron, the patterns are unchanged, it shows no influence from hadronization .,2008.5.24,LHC - IOPP,16,3. A demonstration,Azimuthal correlation pattern in
22、coordinate space,Corr. pattern is in-plane like for all centralities before transpt. (2) All patterns change to out-of-plane like as soon as start to transport, (?) and keep to be out-of-plane like.This maybe the origin of out-of-plane corr. pattern in pt space.,2008.5.24,LHC - IOPP,17, Fourier expa
23、nsion of the correlation pattern:,4. Experimental measure and expectations,: the direction of reaction plane, zero in the model analysis,event- plane in real experimental data analysis.,: provides the preferential direction and strength ofanisotropic correlation pattern. It makes systematicinvestiga
24、tion of correlation pattern easily.,Anisotropic correlation coefficient (ACC),2008.5.24,LHC - IOPP,18, Rapidity dependence of ACC,4. Experimental measure and expectations,Three rapidity intervals:,u2 is independent of observed rapidity windows,in contrary to v2 .,In finite rapidity ranges of current
25、 relativistic heavy ion experiments, studying the correlation pattern and ACC is expectable !,2008.5.24,LHC - IOPP,19, Expectations:,4. Experimental measure and expectations,Case 1: As long as the observed correlation pattern are different from its azimuthal distribution, i.e., what we show bytransp
26、ort models, it would mean that the explanation ofhydrodynamic flow has to be modified !,Case 2: If the experimentally measured correlation pattern has the same anisotropy as its azimuthal distribution, it will be a strong support to the current expectation, which means at intrinsic interaction level
27、 that the formed matter at RHIC indeed behaves like hydrodynamic flow !,2008.5.24,LHC - IOPP,20,5. Summary and conclusions, It is argued that the observation of v2 alone is insufficient to assure whether the formed matter at RHIC behaves like hydrodynamic flow. Examiningthe intrinsic interaction of
28、the formed matter shouldprovide more definite judgment. A spatial-dependent azimuthal multiplicity corr.pattern is suggested. It shows clearly that there are two kinds of interactions at early stage of Au + Au coll. at 200 GeV, generated by RQMD and AMPT . The possibility of experimentally measuring the corr. pattern and ACC is discussed,谢 谢 ！,cf. arXiv: 0801.1149arxiv: 0804.2932,
