1 / 17

Systematic investigation of partonic collectivity through centrality dependence of elliptic flow

Systematic investigation of partonic collectivity through centrality dependence of elliptic flow of multi-strange hadron in Au+Au collision at  s NN =200 GeV in STAR. Md. Nasim (for the STAR Collaboration) Variable Energy Cyclotron Centre Kolkata , India.

knoton
Download Presentation

Systematic investigation of partonic collectivity through centrality dependence of elliptic flow

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. Systematic investigation of partonic collectivity through centrality dependence of elliptic flow of multi-strange hadron in Au+Au collision at sNN=200 GeV in STAR • Md. Nasim • (for the STAR Collaboration) • Variable Energy Cyclotron Centre • Kolkata , India • Outline • Introduction & motivation • STAR experiment at RHIC • Results • Summary Quark Matter Washington D.C August 12-18, 2012 VECC Md Nasim

  2. Elliptic Flow (v2) Initial spatial anisotropy ( ε2 ) Momentum anisotropy( v2) y Py Pressure gradient Interactions Px Pz x Reaction plane P. Klob, U. W. Heinz Nucl. Phys. A715, (2003) 653c • Interactions among constituents transform the initial spatial anisotropy into momentum anisotropy • Process quenches itself → sensitive to early times in the evolution of the system • Sensitive to the equation of state Md Nasim

  3. Motivation • Low interaction cross-section • with other hadrons • BW Model results support • early freeze out of multi-strange • hadrons • Tk ~ Tch ~ Tc( Lattice QCD) • v2( ϕ, Ξ, Ω) is a good probe • of partonic collectivity STAR Collaboration : Nuclear Physics A 757 (2005) Partonic collectivity : Centrality dependence of NCQ scaling Partonic collectivity vs. System size. Hadronic re-scattering effect : v2(p)/v2(ϕ) > 1 ~ mass ordering of v2(hydro-like) < 1 ~ hadronic re-scattering effect STAR Collaboration: Phys.Rev.Lett. 99 (2007) 112301 Comparison of v2(ϕ) with v2(p) can be used to study the effect of hadronic re-scattering. T Hirano et.al Phys. Rev. C 77, 044909 (2008) Md Nasim

  4. STAR Detectors p • Full 2π coverage • Excellent particle identification • capabilities (Using TOF and TPC) K p Data Set: Au+Au 200 GeV, collected in 2010 Total # of analyzed events = 240 M dE/dx clean PID: pion/kaon: pT ~ 0.6 GeV/c and proton pT~ 1.0 GeV/c With TOF : pion/kaon: pT ~ 1.6 GeV/c and proton pT~ 3.0 GeV/c Md Nasim

  5. Multi-strange hadron & v2 measurement Ω -> Λ + K Ξ -> Λ + π ϕ -> K+ +K- • Ω and Ξ are reconstructed by decay topology method + invariant mass method • f-mesons are reconstructed by invariant mass method v2 vs. invariant mass method: Md Nasim

  6. Centrality Dependence Au+Au 200 GeV, η sub EP , Δη = 0.1 unit |y | < 1.0 STAR Preliminary Note : Only statistical errors • Centrality dependence for multi-strange hadrons v2 observed Md Nasim

  7. v2 vs. mT-m0 Au+Au 200 GeV, η sub EP • Centrality 0-30% : • Baryon–meson splitting at intermediate mT-m0. • Centrality 30-80% : • Deviations of multi-strange hadrons from baryons and mesons • groups at intermediate mT-m0. • Multi-strange hadron v2 smaller than other strange hadrons • v2 at mT-m0>1 GeV/c2 (v2(Ξ)<v2(Λ), v2(ϕ)<v2(K0S)) Ref: v2 of π, K , p, K0s and Λ – Poster Presentation by Hiroshi Masui (poster #145) Md Nasim

  8. Number-of-Constituent-Quark Scaling: pT/nq Au+Au 200 GeV, η sub EP • Centrality 0-30% : • f-meson is below from fit line 4 ± 7 % for pT/nq > 1 GeV/c. • Centrality 30-80%: • f-meson is below from fit line 14 ± 5 % for pT/nq > 1GeV/c Md Nasim

  9. (mT-m0)/nq scaling Au+Au 200 GeV, η sub EP • Centrality 0-30% : • f-meson below from fit line 4 ± 6 % for (mT-m0)/nq > 0.6 GeV/c2. • Centrality 30-80%: • f-meson below from fit line 11 ± 4 % for (mT-m0)/nq > 0.6 GeV/c2. Md Nasim

  10. Deviation from K0s STAR Preliminary • f–meson seems to show larger deviation in 30-80% than 0-30% Md Nasim

  11. Mass ordering of elliptic flow Au+Au 200 GeV, η sub EP STAR Preliminary • Mass ordering observed in 0-80%, except between proton and • f-meson for pT < 1.0 GeV/c • Similar trend is observed for 0-30% and 30-80% centrality. Md Nasim

  12. v2(f)/v2(p) vs. pT Au+Au 200 GeV, η sub EP Hydro+Cascade T Hirano, Phys. Rev. C 77, 044909 (2008) • At low pT the v2(f) tends to be higher than v2(p) • for central collisions. This trend is consistent • with the hadronic re-scattering scenario as • proposed in Phys. Rev. C 77, 044909 (2008). • The effect is stronger in central collisions Md Nasim

  13. Summary • First systematic measurement of centrality dependence of multi- • strange hadrons ( ϕ(ssbar),Ξ(dss), and Ω (sss)) at mid-rapidity in • Au+Au collisions at √sNN=200 GeV. • Multi-strange hadron v2 at 30-80% centrality is • smaller than other strange hadrons v2 at • mT-m0>1 GeV/c2 (v2(Ξ)<v2(Λ), v2(ϕ)<v2(K0S)) • f–meson seems to show larger deviation • in 30-80% than 0-30% in NCQ scaling. May indicate smaller contribution to the collectivity from partonic phase in peripheral collisions. • v2(f)/v2(p) tends to be greater than unity • at low pT. • Consistent with hadronic re-scattering • effect as proposed in theoretical model. Md Nasim

  14. Back-up Md Nasim

  15. Md Nasim

  16. Number-of-Constituent-Quark Scaling: pT/nq Au+Au 200 GeV, η sub EP Md Nasim

  17. (mT-m0)/nq scaling Au+Au 200 GeV, η sub EP Md Nasim

More Related