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Measurement of Heavy Quark production at RHIC-PHENIX

Measurement of Heavy Quark production at RHIC-PHENIX. Yuhei Morino CNS, University of Tokyo. flow & energy loss ? insight into the property of the medium. 1.Introduction. RHIC is for the study of extreme hot and dense matter. p+p, d+Au, Cu+Cu, Au+Au collision

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Measurement of Heavy Quark production at RHIC-PHENIX

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  1. Measurement of Heavy Quark production at RHIC-PHENIX Yuhei Morino CNS, University of Tokyo

  2. flow & energy loss ? • insight into the property of the medium 1.Introduction • RHIC is for the study of extreme hot and dense matter. • p+p, d+Au, Cu+Cu, Au+Au collision • √s = 22.4, 62, 130, 200 GeV A. • Heavy quarks (charm and bottom) is produced in initial collision • good probe for studying property of the medium. • small energy loss and large thermal equilibration time are expected due to their large mass.

  3. 2.PHENIX experiment • PHENIX central arm: • |h| < 0.35 • Df = 2 x p/2 • p > 0.2 GeV/c • Charged particle tracking analysis using DC and PC → p • Electron identification • Ring Imaging Cherenkov detector (RICH) • Electro- Magnetic Calorimeter (EMC) → energy E

  4. 3.Heavy quark measurement at PHENIX electron/muon from semileptonic decay direct measurement: DKp, DKpp p+

  5. PRL, 97, 252002 (2006) Upper limit of FONLL 3.2 Result of p+p at sNN = 200 GeV Inclusive electron ( g conversion, p daliz,etc and heavy quark ) Background subtraction Non-photonic electron (charm and bottom) • scc= 567 ± 57(stat) ± 224(sys) mb • FONLL: Fixed Order plus Next to Leading Log pQCD • Central value for data/FONLL predictions ~1.7 ( reasonable value)

  6. MB 0%~ ~92% p+p 3.3 Result of Au+Au at sNN = 200 GeV PHENIX PRL98 173301 (2007) Heavy flavor electron compared to binary scaled p+p data (FONLL*1.71) Clear high pT suppression in central collisions

  7. 3.4 Nuclear Modification Factor: RAA large suppression! PHENIX PRL98 173301 (2007) Djordjevic, PLB632 81 (2006) • Radiative energy loss • does not describe!. • dead cone effect

  8. Greco, Ko, Rapp: PLB 595 (2004) 202 data suggests non-zero charm v2  charm is strongly coupled to the matter. 3.5 Non-photonic electron v2 pQCD fail [PRB637,362]

  9. PLB649(2007)139 Collisional dissociation heavy quarks can fragment • inside the medium and can • be suppressed by dissociation be RAA ce RAA 3.6 comparison with models. various models exist. • pQCD radiative E-loss with • 10-fold upscaled transport coeff. • elastic pQCD + D resonances • + coalescence • 2-6 upscaled pQCD elastic behavior of bottom differ from charm c/b separation is necessary for further discussion. These calculations suggest that DHQ (~(3~6)/2pT..near quantum bound) are required to reproduce the data.

  10. 4. B contribution to non-photonic electron FONLL: • FONLL: • Fixed Order plus Next to Leading Log pQCD calculation • Large uncertainty on c/b crossing 3 to 9 GeV/c Experimental determination of ce/be is one of most important next steps

  11. Heavy quark measurement at PHENIX electron/muon from semileptonic decay D e K n partial reconstruction p+

  12. 5 ce/be via e-h correlation unlike sign e-h pairs contain large background from photonic electrons. like sign pair subtraction (Ntag is from semi-leptonic decay) Ntag = Nunlike - N like From real data analysis Nc(b)e is number of electrons from charm (bottom) Nc(b)tag is Ntag from charm (bottom) edata can be written by only charm and bottom component From simulation (PYTHIA and EvtGen) The tagging efficiency is determined only decay kinematics and the production ratio of D(B)hadrons to the first order(85%~). • production ratios (D+/D0, Ds/D0 etc) • contribution from NOT D(B) daughters Main uncertainty of ec and eb 

  13. 5.2 ce/be via e-h correlation theoretical uncertainty is NOT included. Year5 p+p s=200GeV data set is used comparison of data with simulation (0.5~5.0 GeV) pt(e) 2~5GeV/c c2 /ndf 58.4/45 @b/(b+c)=0.34

  14. (b max) and (c min) (b min) and (c min) (b max) and (c max) (b min) and (c max) 5.3 ce/be via e-h correlation Year5 p+p s=200GeV data set is used (be)/(ce+be) as a function of electron pt

  15. Heavy quark measurement at PHENIX direct measurement: D0K+p-p0 D0K+p- p+

  16. 6. Direct measurement of D0 D0K+p-p+ reconstruction • Year5 p+p s=200GeV data set is used • Observe 3s significant signal in pT D range 5 ~ 15 GeV/c • No clear signal is seen for pT D < 5 GeV/c • The signal is undetectably small for pT D > 15 GeV/c • Signal is fitted with parabola(B) + gaussian(S)

  17. Momentum Dependence 6.2 Direct measurement of D0 D0K+p-p+ reconstruction Analysis to determine invariant cross section is on going. Observe clear peak in all pT bins from 5 GeV/c to 10 GeV/c Fits are parabola + gaussian Background is uniform within fitting range

  18. 6.3 Direct measurement of D0 D0K+p- reconstruction with electron tag Year5 p+p s=200GeV data set is used real event mixing event back ground subtracted tag • observe D0 peak • Analysis to determine invariant cross • section is on going reconstruct

  19. Summary and outlook • A large suppression pattern and azimuthal anisotropy of single electron has been observed in Au+Au collisions at √sNN=200GeV. • be/(ce + be) has been studied in p+p collisions at √s =200GeV via e-h correlation for further discussion.  analysis for more statistics and high pt extension is on going • Clear peak of D0 meson observed in p+p collisions at √s =200GeV in D0K+p-p0 and D0K+p-channels. Analysis to determine invariant cross section is on going. The results of direct measurement will be compared with the results of measurement via semi-leptonic decay

  20. back up

  21. Singnal and Background Photonic Electron • Photon Conversion Main photon source: p0 → gg In material: g → e+e- (Major contribution of photonic electron) • Dalitz decay of light neutral mesons p0 → g e+e- (Large contribution of photonic) • The other Dalitz decays are small contributions • Direct Photon (is estimated as very small contribution) • Heavy flavor electrons (the most of all non-photonic) • Weak Kaon decays Ke3: K± → p0 e±e (< 3% of non-photonic in pT > 1.0 GeV/c) • Vector Meson Decays w, , fJ → e+e-(< 2-3% of non-photonic in all pT.) Non-photonic Electron

  22. Background Subtraction: Cocktail Method Most sources of background have been measured in PHENIX Decay kinematics and photon conversions can be reconstructed by detector simulation Then, subtract “cocktail” of all background electrons from the inclusive spectrum Advantage is small statistical error.

  23. Ne Electron yield converter 0.8% 0.4% 1.7% With converter Photonic W/O converter Dalitz : 0.8% X0 equivalent radiation length Non-photonic 0 Material amounts: 0 Background Subtraction: Converter Method We know precise radiation length (X0) of each detector material The photonic electron yield can be measured by increase of additional material (photon converter ) Advantage is small systematic error in low pT region Background in non-photonic is subtracted by cocktail method

  24. Consistency Check of Two Methods Both methods were checked each other Left top figure shows Converter/Cocktail ratio of photonic electrons Left bottom figure shows non-photon/photonic ratio

  25. X 1/Nnon-phot e From real data edata 0.029 +- 0.003(stat) +- 0.002(sys) count Electron pt 2~5GeV/c Hadron pt 0.4~5.0GeV/c unlike pair like pair bottom production charm production 4. Analysis(2) From simulation (PYTHIA and EvtGen) charm ec = 0.0364 +- 0.0034(sys) bottom eb = 0.0145 +- 0.0014(sys) Electron pt 2~5GeV/c Hadron pt 0.4~5.0GeV/c unlike pair like pair (unlike-like) /# of ele

  26. 5. Result (electron Pt 2~3GeV/c) theoretical uncertainty is NOT included. comparison of data with simulation (0.5~5.0 GeV) pt(e) 2~5GeV/c c2 /ndf 58.4/45 @b/(b+c)=0.34 pt(e) 2~3GeV/c c2 /ndf 34.3/22 @b/(b+c)=0.28

  27. 5. Result (electron Pt 3~4GeV/c) theoretical uncertainty is NOT included. comparison of data with simulation (0.5~5.0 GeV) pt(e) 2~5GeV/c c2 /ndf 58.4/45 @b/(b+c)=0.34 pt(e) 2~3GeV/c c2 /ndf 34.3/22 @b/(b+c)=0.28 pt(e) 3~4GeV/c c2 /ndf 13.4/22 @b/(b+c)=0.66

  28. 5. Result (electron Pt 4~5GeV/c) theoretical uncertainty is NOT included. comparison of data with simulation (0.5~5.0 GeV) pt(e) 2~5GeV/c c2 /ndf 58.4/45 @b/(b+c)=0.34 pt(e) 2~3GeV/c c2 /ndf 34.3/22 @b/(b+c)=0.28 pt(e) 3~4GeV/c c2 /ndf 13.4/22 @b/(b+c)=0.66 pt(e) 4~5GeV/c c2 /ndf 21.9/22 @b/(b+c)=0.75

  29. 6.Discussion Collisional dissociation in hot and dense matter? heavy quarks can fragment • inside the medium and can • be suppressed by dissociation Input be/ce suppression of non-photonic electron is not so strong as prediction by collisional dissociation model.

  30. Open Charm in p+p STAR vs. PHENIX PHENIX & STAR electron spectra both agree in shape with FONLL theoretical prediction Absolute scale is different by a factor of 2 31

  31. Bottom ! • Fit e-hcorrelation with PYTHIA D and B • Data shows non-zero B contribution p+p 200 GeV STAR QM2006

  32. e+ e- Photon Converter

  33. page4 Non-photonic electron v2 measurement • Non photonic electron v2 is given as; (1) (2) v2e ; Inclusive electron v2 =>Measure RNP = (Non-γ e) / (γ e) => Measure • v2γ.e ; Photonic electron v2 • Cocktail method (simulation)stat. advantage • Converter method (experimentally)

  34. page6 Inclusive electron v2 • inclusive electron v2 measured w.r.t reaction plane • converter --- increase photonic electron • photonic & non-photonic e v2 is different

  35. page7 Photonic e v2 determination v2 (π0) R = N X->e/ Nγe pT<3 ; π (nucl-ex/0608033) pT>3 ; π0 (PHENIX run4 prelim.) decay • photonic electron v2 • => cocktail of photonic e v2 photonic e v2 (Cocktail) • good agreement • converter method • (experimentally determined)

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