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Electron Flow in AuAu@200GeV

Electron Flow in AuAu@200GeV. Frank Laue ( laue@bnl.gov ) for the STAR Collaboration. Outline Motivation Analysis (Preliminary) Results Outlook. 200GeV (old) Au+Au minimum bias trigger. Motivators. Kai Schweda STAR QM2004. All mesons behave the same All baryons behave the same

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Electron Flow in AuAu@200GeV

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  1. Electron Flow in AuAu@200GeV Frank Laue(laue@bnl.gov) for the STAR Collaboration • Outline • Motivation • Analysis • (Preliminary) Results • Outlook 200GeV (old) Au+Au minimum bias trigger

  2. Motivators Kai Schweda STAR QM2004 • All mesons behave the same • All baryons behave the same • Mesons behave differently from baryons • NCQ scaling • dynamic governed by partonic phase, which is observed after coalescence/recombination of quarks ? Frank Laue, BNL (laue@bnl.gov)

  3. Motivators Fries,Mueller,Nonaka,Bass nucl-th/0308051 • NCQ scaling doesn’t work everywhere ? • v2 is very sensitive probe Frank Laue, BNL (laue@bnl.gov)

  4. Questions/Problems • Data suggests NCQ scaling (coalescence,recombination) for Elliptic Flow and RCP ! Partonic Phase (hey, ho the QGP!) • What about hydro-dynamics ? (governed by mass, not NCQ) • successful spectra (Tkin,f), Nu Xu plot (Teff vs mass)!radial flow • Radial / Elliptic Flowboth caused butpressure, shouldn’t they scale similarly ? • Why does NCQ scaling works so good at higher pT (phasespace scarcely populated, coalescence less likely) • s(trongly interacting)QGP, parton-hydrodynamics ? • u,d¼ 5MeV; s¼150MeV, c¼1.5GeV • ! look at charm, both in partonic and hadronic world the charm is very heavy; should be very sensitive Frank Laue, BNL (laue@bnl.gov)

  5. Line of Thought • Can not measure Charm-Flow directly (yet) • Do D-Meson decay electrons reflect the D-Meson flow ? • Electron Identification • Where do the Electrons come from ? • Backgrounds from • misidentification (contamination) • physics processes (0! e+e- +  B.R. 1.198%) • detector effects ( ! e+e- : few %, dep. on material) Frank Laue, BNL (laue@bnl.gov)

  6. Do Decay-Electrons Reflect the Parent Flow ?Electron vs D Momenta pD-Meson (GeV/c) pD-Meson (GeV/c) pelectron (GeV/c) pelectron (GeV/c) Frank Laue, BNL (laue@bnl.gov)

  7. Do Decay-Electrons Reflect the Parent Flow ? vs D Momenta D-Electron D-Electron pD-Meson (GeV/c) pelectron (GeV/c) Frank Laue, BNL (laue@bnl.gov)

  8. Do Decay-Electrons Reflect the Parent Flow ?Pythia/Mevsim Simulation • 0 (input) • e§ v2 % v2 % • D0 (input) • e§ pT / (GeV/c) pT / (GeV/c) Frank Laue, BNL (laue@bnl.gov)

  9. Fraction of electrons from: • 0! e+ + e- +  • D ! e§ + X d2N/(dpdy) (a.u.) F pelectron (GeV/c) pelectron (GeV/c) Where Do The Electron Come From ?(Pythia) Frank Laue, BNL (laue@bnl.gov)

  10. Where Do The Electron Come From ?(Pythia, STAR Simulation/Analysis Chain) Pythia 6.2 Heavy Quarks turned on GStar Reconstruction Track Associations  0 , D0,D§ | eta | < 1 DCA < 2cm 23 < #fit-Points < 100 20 < #dEdx-Points < 100 K0L K0 Frank Laue, BNL (laue@bnl.gov)

  11. - + dE/dx/(KeV) dE/dx/(KeV) log10(p/(GeV/c) log10(p/(GeV/c) TPC dE/dx vs p e+ Frank Laue, BNL (laue@bnl.gov)

  12. Electron Selection • “clean” electrons between the blue lines •  conversion removed via invariant mass method (~50% efficiency) Frank Laue, BNL (laue@bnl.gov)

  13. - dE/dx/(KeV) log10(p/(GeV/c) Deuteron Contamination (preliminary) <20% contam raw-yield p/(GeV/c) • 2x as many deuterons and anti-deuterons • 2x(3) more electrons(positrons) than extrapolated (anti-)deuterons • more than ½ of (anti-)deuterons out of dEdx band Frank Laue, BNL (laue@bnl.gov)

  14. dN/dmass v2 % pT/(GeV/c) mass/(GeV/c2) -conversions and 0-Dalitz Decays 0! e+ + e- +  ~50-80% of ’s can be removed with invariant mass method Frank Laue, BNL (laue@bnl.gov)

  15. black = electrons+positrons electrons positrons V2 vs pT pT/(GeV/c) cos(2(-)) pT/(GeV/c) Frank Laue, BNL (laue@bnl.gov)

  16. STAR Preliminary PHENIX PRELIMINARY Flow of electrons (charm): v2 from PHENIX & STAR Slightly different dE/dx cut: 3.4<dE/dx<5.0 • Au+Au @200GeV • Run II • Run IV (fast offline) Frank Laue, BNL (laue@bnl.gov)

  17. Outlook / To-Do-List • Quantitative measurements • contaminations and background (yields) • measure flow of contam./ background • ! non-photonic v2 • deuteron flow (constituent model) • 100x better statistics in Run IV (already on tape) • centrality dependence • reduce backgrounds by 80% with tighter cuts • EMC electron analysis is already prepared • too low statistics for 62GeV • higher pT , bkg reduction • Pixel Vertex Detector (¼ 100m Vertex Resolution) • (almost) background free identification of D/B-Mesons Frank Laue, BNL (laue@bnl.gov)

  18. Yields vs (phi-psi) black = electrons red = fit to electronsblue = hadrons Frank Laue, BNL (laue@bnl.gov)

  19. Electron v2 all charges electrons positrons Frank Laue, BNL (laue@bnl.gov)

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