1 / 19

Anisotropic flow at RHIC: How unique is the NCQ scaling ?

Anisotropic flow at RHIC: How unique is the NCQ scaling ?. Feng Liu Yan Lu. Institute Of Particle Physics CCNU , Wuhan. M. Bleicher, P. Sorensen, H. Stöcker, N. Xu, X. Zhu J. Phys. G32 , 1121(2006). Outline. Motivation Model study v 2 dependent on

twila
Download Presentation

Anisotropic flow at RHIC: How unique is the NCQ scaling ?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Anisotropic flow at RHIC: How unique is the NCQ scaling ? Feng LiuYan Lu Institute Of Particle Physics CCNU , Wuhan M. Bleicher, P. Sorensen, H. Stöcker, N. Xu, X. Zhu J. Phys. G32, 1121(2006) Quark Matter 2006, Shanghai China

  2. Outline • Motivation • Model study v2 dependent on centrality, pT and time of freeze-out • Summary Quark Matter 2006, Shanghai China

  3. High-energy Nuclear Collisions time Hot and Dense Initial conditions and interactions Cooling down freezing out Experimental probes: 1) Energy loss 2) Elliptic flow, radial flow … Quark Matter 2006, Shanghai China

  4. y py px x Anisotropy parameter v2 Sensitive to initial/final conditions and equation of state (EOS) ! coordinate-space-anisotropy  momentum-space-anisotropy v2 :a probe of the dynamics governing the system’s evolution Flow :represents the collective motion of particles. Quark Matter 2006, Shanghai China

  5. Identified particle v2 at 200 GeV PRL 92(04) 052302 • v2 appears to saturate at ~0.13 for KS and ~0.20 for  with the saturation setting in at different pT. Quark Matter 2006, Shanghai China

  6. Number of constituent quark scaling Scaling works with kaons, protons, lambdas and cascade. Pions differ from scaling may due to resonance decays. X. Dong et al, PLB597 328 Quark Matter 2006, Shanghai China

  7. NCQ-scaling: Partonic flow In this scenario we can infer the value of the parton v2 in the relevant pT region (~7%). Quark Matter 2006, Shanghai China

  8. coalescence • Produced particles are • hadronized via coalescence • v2 follows the scaling with Number of Constituent Quarks(NCQ): (n=2), (n=3) Models: R. Fries et al, PRC68, 044902(03) Coalescence hinting system is partonic, hadrons are formed at the boundary of parton and hadron Quark Matter 2006, Shanghai China

  9. Motivation measure v2 and RAA,RCP for PID particles hadrons formed via the coalescence of quarks cornerstone:observed NCQ scaling of v2 interpretation addresses key issues systematic study other possible explanations Questions: • Is this a unique ? • What is v2 in the hadronic model ? • How about the contributions of re-scatterings at the hadronic stage? Quark Matter 2006, Shanghai China

  10. hadron-string transport Model study of v2 UrQMD(v2.2), RQMD (v2.4): successful in predicting most of observed features of integrated bulk property Model features and utilization 1 Switch on/off re-scattering among particles to study whether re-scattering is important ? 2 With hadronic but without partonic re-scattering. to study influence on the results without partonic re-scattering. Quark Matter 2006, Shanghai China

  11. Almost zero.Even though initial space anisotropy exists,momentum anisotropy can’t be converted into. Reproduce the trend of experiment but have smaller value than experiment’s. 1 Re-scatterings are necessary. 2 Re-scatterings at partonic level are essential. Originates from at partonic stage? Quark Matter 2006, Shanghai China

  12. earlylate Temporal Structure of the v2’s development Flow originates in the model with re-scatterings. Strong correlation between freez-out time and v2 v2 decrease with pressure gradient( time) Quark Matter 2006, Shanghai China

  13. correlation between freeze-out time and elliptic flow 1 Decrease with pressure gra- dient(time). 2 re-scattering resists the trend of decrease. The higher- pT particle ‘s v2 decreases more slowlier. earlier stage of the collision more strongly Balance of the two effect (saturation) At RHIC,the stronger and more frequent re-scatterings among partons at very early stage lead to saturate at higher pT. Quark Matter 2006, Shanghai China

  14. Identified elliptic flow pT dependence of v2 Compared to data, main features are reproduced low pThydrod behaviour intermediate pT hadron-type dependence v2 increases with pT and then saturates(or decrease) NCQ is not unique hadronic interactions predicted hadron-type dependence. Quark Matter 2006, Shanghai China

  15. pT dependence of identified v2 Low pTmass ordering, hadronic interactions contribute to collective motion. higher pT, hardon type dependence pT > 2.5 GeV/c, v2 decrease. NCQ scalling Quark Matter 2006, Shanghai China

  16. pT dependence of identified v2 angular-dependent matter density gradient. push matter move outwards collective flow Σsuper-surface where hadrons are emitted σinteraction cross section ~ additive quark model low pT re-scattering → hydro-like mass ordering Quark Matter 2006, Shanghai China

  17. pT dependence of identified v2 pT>1.5 GeV/c lack of development of hydrodynamics σ are most important; 2:3 scaling for M-B distinguishable differences between two NCQ Coalescence: identical elliptic flow of all baryons AQM scaling ordering of the elliptic flow at fixed pTaccording to the strangeness content. v2(N) > v2(Λ) > v2(Ξ) > v2(Ω) Quark Matter 2006, Shanghai China

  18. Summary • v2 dependent on centrality,pT and t are studied. • re-scatterings are necessary for development of • collective elliptic flow • model has smaller v2 than experiment • partonic collective motion are important at RHIC • at intermediate pT ,hadron-type dependence is • produce by hadronic transport model • NCQ scaling isn’t a unique deconfinement mechanism • high precision v2 measurement are necessary Quark Matter 2006, Shanghai China

  19. Cross sections: AQM Quark Matter 2006, Shanghai China

More Related